Played around a bit with Avatar running in 3d at the Taipei Game Show recently. It was pretty meh for me, but my other two buddies quite enjoyed it. Found it really blurried things up, although it could have been an added effect to increase the perceived depth-of-field. The flying sequences were much cooler with 3d, but the third person stuff didn't really add to much to the experience, and kind of confused things when foliage and stuff came too close to the front plane, obscuring much more of the visual field than I would have liked.
Also, they had Assassin's Creed running on one of those glasses-less 3d tvs. Hard to judge it as the game was only running at maybe 5 fps, but the 3d effect was very minimal, and only really noticeable when you were standing directly in front of it from about six to eight feet away. Even then it could not visually compare to the 3d effect with glasses.