I finally saw the film Religulous - I have to say I was disappointed. Bill Maher asks someone a question, then interrupts the answer with "Do you really believe in a talking snake?" and such comments. I think it would have been a more interesting film if he had kept quiet and let the crazies speak for themselves. The best part was when he found a wacky priest outside the Vatican who essentially repudiated all Catholic theology: "Hell? Pfft! That's the old Catholicism!"
The low point was certainly when Maher threw out a bunch of pagan parallels, every single one of which was completely bogus. Probably his research consisted of ten minutes Googling. This sort of thing just plays into the hands of the religious: it's easy to show these claims are false, and thus dismiss Maher as a liar or ignoramus.
Still, I think Maher's approach (like PZ's) is worth the effort. Sometimes a good snort of derision is enough to make someone see the other side. I remember my freshman year of college, when I still thought young-earth creationism was a logically valid option - after all, God could have made those dino fossils and hidden them in the ground, couldn't he? My roommate, not unkindly, said something like, "You don't really believe that, do you?" That was enough to allow me to look at the idea from the outside, so to speak, and realize what extreme special pleading it was.