Anyway, the existence of "fine-tuning" in the universe (in the sense of various parameters being narrowly balanced to produce life) is well known among the physics community, theists and non-theists alike. But surely you realize that there is a world of difference between "fine-tuning" and "intelligent design", and that the latter does not logically follow from the former? And the claim "either the Universe was designed specifically for us by a creator or there is a multitude of universes" is clearly a false dichotomy -- there are other possibilities, perhaps more plausible than either of those two.
Sure, the parameters are "fine-tuned" to produce life, but who says that the parameters could have taken on any other values in the first place?? If you're going to say that it's "improbable" that such a universe could have arisen, you must presuppose that the universe could have evolved some other way, but we have no information whatsoever on how, if at all, that may have occurred. It could be a law of physics that the constants could only take on the values that they do, for all we know! And we don't know, so we shouldn't presume to know. (Creationists always implicitly assume that they could take on any values, when in fact we don't know one way or the other. It's always dangerous to assume things that you can't possibly know.) It is certainly fallacious to assume that the parameters could take on any independent values; some of them are probably related, and the rest still might not be capable of taking on any real value from negative infinity to positive infinity with equal probability.
(For example, before Maxwellian electromagnetism, the permittivity of free space, permeability of free space, and the speed of light in vacuo were all thought to be independent constants, but with the unification of electricity and magnetism, they were all shown to be related; you cannot vary all three of them independently. Further unifications in physics may lead to even fewer free parameters.)
The same goes for the laws of physics themselves. Who says it's even possible for the universe to exist in dimensions other than four? It's very likely might not be; there are many mathematically unique things about four dimensions, and the same laws of physics simply might not exist at all with any other number -- they might not generalize to arbitrary dimensions. It would thus make no sense to say that the universe is "fine-tuned" to four dimensions, since it couldn't be any other way.
Second, even if the parameters were fine-tuned, who says that the "fine-tuner" is intelligent? The universe could fine-tune itself. Self-organizing critical systems are capable of fine-tuning all by themselves, following only a simple set of physical laws -- thus making it likely that the parameters are "fine-tuned" the way we see them.
Lee Smolin is attempting to verify such a theory, which he calls "cosmological natural selection". (This is a real, falsifiable physical theory. Quantum gravity would be required to support some of its basic hypotheses, but is not required to support its predictions. So far it has passed the tests which have been applied to it, though that's by no means conclusive.) Cosmological natural selection makes predictions -- for example, it predicts that we should expect universes with stars to be highly probable. And Nielsen's random dynamics theory has demonstrated that if you assume that the universe is being balanced at a critical point of a phase transition, it almost doesn't matter at all what the Planck-scale laws of physics are (you just need to make a few additional, rather broad general assumptions); they will necessarily lead to observed macroscale physics in many ways (e.g., a gauge theory of a 4D spacetime obeying quantum mechanics) even if you chose the laws at random. (Though there are still plenty of things that random dynamics can't currently explain.) Etc. Appealing to an intelligent designer to explain "fine-tuning" is hardly a necessity.
Claiming that "fine-tuning" of the universe's parameters requires intelligent design is exactly as fallacious as claiming that the "fine-tuning" of biological structures requires intelligent design; natural selection and evolution allow such structures to self-organize by themselves using only natural laws of dynamics. (Of course, applying this argument to the universe presupposes that it is possible for the parameters of the universe to change. Such "dynamically generated" laws are certainly possible, and there are various theories including them, but they have not been experimentally confirmed -- though their consequences may be tested, as Smolin is doing.)
Of course the theories I've mentioned are still rather speculative, but they certainly show that an intelligent designer is not a logical necessity. (And they also don't require a "multitude of universes" or "multiverse".) And even if you did come up with some way of proving that an intelligent designer is the most probable explanation (not bloody likely) for the parameters of the universe, that doesn't mean that the designer needs to have intentionally designed us -- maybe the universe was designed specifically to produce howler monkeys or Venusian tree smoots, and human beings are just a byproduct. (I believe there is a famous quote pointing out that based upon their numbers and how suitable conditions on Earth are for them, the evidence points to God having created the Earth for cockroaches. Conditions here are certainly more favorable to them than to us; we are adapted to naturally survive only in a comparatively narrow range.) Or maybe the universe was designed to merely be one likely to give to rise to life, and human beings were not specifically designed for.
And for that matter, it doesn't mean that this designer needs to be omnipotent (though maybe so in this universe), omniscient, eternal, benevolent, personal, intervene directly in human affairs, or in any way be related to, say, the Christian god. For all we know, the designer could be Bhrama, Allah, the Buddha, Satan, the IPU, Queen Maeve, Richard Simmons, or an extradimensional teenage alien (for his science fair project, "A Computer Simulation of Intelligent Life and a Study of Their Origin Beliefs" -- unfortunately not taking the prize since the judges thought that whole "religion" thing in his report on the natives was too absurd to have arisen in a real simulation of a physical system; sadly, even extradimensional beings have been known to resort to a little implausible fabrication now and then to spice up an otherwise dull project). The false dichotomy of "either the universe arose naturally, or it arose from the Christian god" is a common one among creationists.
Third, even if this universe is wildly improbable, so what? By the anthropic principle, if it were different we wouldn't be here to wonder about it. The constants being what they are are a necessary condition for our existence; if only one out of a trillion universes gave rise to life, then there would be 999,999,999,999 empty universes and one with beings saying "wow, what a coincidence!" even though it was completely due to chance.
It makes no sense to say, as is often argued, "yes, but an intelligent designer is a more likely hypothesis than a trillion-to-one chance of the parameters randomly coming out that way", since you have no way of assigning a probability to that. For all we know, the odds of an intelligent designer existing are a googol to one. (You could attempt to argue that the number of people who believe in one form of religion or another speaks of its high probability, but there is no demonstrable correlation between that number and the numerical probability of that hypothesis being true.) And even if we had reason to believe that an intelligent designer was the more likely hypothesis, that still doesn't mean that it's true, unless the probability is 1.
Furthermore, current cosmological evidence suggests that the universe is infinite in spatial extent. That means that if it's possible for life to evolve in 15 billion years, no matter how low the probability, then it almost certainly will evolve somewhere or other in an infinite universe. (Again, with the beings wondering "wow, what a coincidence" though it is again purely a chance occurrence.) If the many-worlds interpretation of quantum mechanics happened to be true (and we have no way of knowing, so I'm really not proposing it as a scientific argument), every possible universe exists so life could certainly arise purely by chance.
It's like rolling a die ten times and getting 3526525514 and saying "wow, the odds on that were 60 million to one, what a coincidence!!". (And note that rolling 6666666666 is no less likely; the probability of getting 3526525514 is exactly the same as the probability of getting 6666666666.) If you post facto single out some particular sequence as "special" (such as "6666666666" or "life arising") then of course that individual sequence is improbable, but that doesn't mean that the dice were rigged (i.e., there was an intelligent designer behind that sequence). It's exactly as probable or improbable as anything else.
Sure, non-life producing universes might be more probable than life-producing ones, but what does that prove? We only think that life-producing universes are special because we're in one. Each individual universe, life-producing or not, has the same intrinsic probability. The "intelligent design" argument is highly anthrocentric -- it only works if you assume that life-producing universes are special in some way that affects the production of those universes.
For example, suppose that you allow two compartments of randomly-distributed gas molecules to mix together, and then at some instant after a long period of time you take all the molecules in one corner and paint them blue to indicate that this configuration is "special". Then you claim that the initial configuration of the gas molecules must have been set in just such a way that all of the molecules which you later painted -- which surely were distributed almost at random in the beginning -- happen to end up, at that later instant, to all end up in one corner of the compartment. After all, if it had been set up any other way, if the initial distribution of gas molecules in the two compartments had been almost anything else, those particular molecules which you've painted blue would never have ended up in that corner all at once by that time. What are the odds of that happening, that those particular molecules all end up in that corner at that time? About a gazillion to one. That must mean that the initial configuration of molecules was intelligently designed so that those molecules would end up there at that time, right? Wrong. The initial configuration of molecules was random.
This is exactly analogous to what people claim when they suggest that "fine-tuning" must imply intelligent design. You after the fact designate some particular configuration of the system as "special", such as "those molecules in the corner" or "the existence of life on Earth", and say "Wow, things must have been set up in the beginning exactly so that this configuration will occur!". But it's really an artifact of our singling out one configuration as special. It's exacerbated if this configuration happens to give rise to self-aware life -- if all of those molecules in the corner happen to, through their interactions, give rise to some sort of sentient behavior, then they might suppose that the initial distribution of gas in the compartment was "fine-tuned" to make all of them end up in that corner at that particular time.
As a similar example, look at it this way: suppose hypothetically that the parameters of the universe were determined purely at random by some natural physical process (without intelligent design being involved), such as a quantum fluctuation or something. Further suppose that there are 10 such parameters, which can take on values between 1 and 6, with every permutation being equally likely. And finally suppose that the only configuration of parameters capable of giving rise to a universe with intelligent life is 3526525514, and that the universe happens to, by random, come up with that configuration. To us, those parameters are a meaningless and random sequence, no more and no less likely than any other. But to them, it's an extremely special, unique, and very improbably "fine-tuned" -- the odds are worse than 60 million to one! -- set of parameters. But it would be incorrect for them to conclude that their universe was intelligently designed, because in this hypothetical example, it wasn't! (And again, this does not require a "multiverse".) No matter what configuration actually occurs, you can always after the fact say that that configuration was "selected for" simply by virtue of it being so improbable and you being in it, when in fact it's no more improbable than any other!