Because Nvidia can support PS 3.0 with its new flag ship doesn’t mean it can run it at a playable framerate, it’s the 1st release and I am sure it will run at an unplayable framerate IE @25FPS or lower. But since there is no PS3.0 games out yet and only thing on the horizon is Furturemark's 3Dmark 04 that will be using some PS3.0, there is no way to benchmark it.
Both cards have there pluses and minuses, if you play mainly OpenGL(Call of duty) games then the NVIDIA card is the best choice for you, But if you play current DX9(Far Cry and Splinter Cell) and some DX8 games then the ATi may be the best. I have read about 6 reviews from several hardware site and most of the time the Ati comes out on top. NVIDIA has a huge power requirements, Nvidia Recommends a PSU @ least 480 Watts and it takes up a PCI slot, and runs hot. Ati on the other hand runs cooler, only takes one Slot(AGP) and doesn’t require a 480WATT PSU or higher.. The Ati X800 XT for this round is the card for me and the "type" of gaming that I do.