Huh, 3D will require twice the framerate, and most computers could barely squeek out a playable 30FPS for the first game. Still, 3D is the logical progression of SLI/Crossfire, if you already have each card render every other frame (depending on the mode), nothing says it has to do it from the same angle. The entry cost though is just too much (special monitor + graphics card(s) + glasses -OR- console + TV + glasses). However, if they make it truly playable in 3D mode, it will be even more playable for those of us sticking with 2D.
Roger Ebert had a really good article about how 3D is just the current gimmick being used by Hollywood to try to get people into theaters (where the real money is made). With BluRay and HDTVs over 60" in retail stores, people don't need to go to theaters to see a big-screen and high-definition movie. 3D is a marketing ploy to offer something in the theaters you can't get at home (in the early days, it was moving pictures in general, then it was air conditioning, then color, then picture size/quality, then surround sound, now 3D). I'm not sure what Hollywood will do if 3D TVs take off (I don't think they will), but it won't be pretty.