Don't have time to read through all 4 pages of comments, so if this has been said already, I apologize, but:
How is a dual projector setup at all cool? The only, ONLY plausible pro I can come up with is that you could get 1080p output. But if the non-Nvidia drivers are worse for gaming and you can't do Blu-ray 3D period, what's the point of having the extra pixels?
I'm utterly perplexed by this notion of a "3D gaming party" where you have 15+ people in a room all watching one person play a game. As nerdy as I am, I struggle to think of a case where you would ever, ever want to do that outside of a promotional event. I feel weird enough having one person watch me play a game, to say nothing of having 15. You would need a truly massive room to have seating space for 15 people in the area where 3D won't look distorted and weird. We're talking a purpose-built room at this point. And so... so what? So you can invite your friends over and they can watch you do a raid on WoW (oh wait, no mouse). Maybe an exciting match of Starcraft II (wait! No mouse!)? I guess you could play... Modern Warfare 2? Maybe I just don't have enough friends, but I couldn't get 15 people to watch me play any game for any length of time. And when you factor in that about half the population of nerds seems to be disgusted at the idea of 3D, with or without glasses...
I just don't see how it's practical in the slightest. The main use of cheap glasses and large crowds of people, I have been lead to believe, is for watching the upcoming wave of Blu-ray 3D movies. You can't do that with the drivers that support dual projectors.
By the numbers, there's a $1500 discrepency between the Nvidia solution and the competing solutions. $1500 = 10 more pairs of polarized glasses at today's prices, probably 15 pairs if you do your setup in a year's time. I would be genuinely shocked if there were even 1000 people in the entire US who EVER had groups of 11+ people who simultaneously wanted to watch somebody play a game in 3D.
So it seems that the dual projector setup is less cost-effective, more complicated, has worse game support, has no 3D movie support, and requires a dozen 3D enthusiasts to be in a single room before it yields a single benefit.
Am I missing something here?