well either way, I won't be buying it for xbox2.
besides, PC graphics card's will be well beyond Xbox 2, (2x SLI 6800 gt's) by the time it comes out. although it might be cool if they came out with a mouse/keyboard set up for it. As far as I'm concerned, we've got a long enough wait ahead, that many thing's can change.
One thing about the xbox2 that puzzles me though (correct me if I'm wrong here) is that it probably should have been out by now.
I mean, wasn't the xbox, which had the nv 25/2a gpu (faster than the GF3) released around the time of the GF3?. Wasn't the point of it to attract pc users to convert, to M$crosoft Mach$ne...but failed?.
I guess what I'm trying to say is that, now that I have a 6800 ultra with sm3.0 support, why would I want a console with an r500 for anything other than console only games?. The Xbox had a chance because it was equal to the pc, but by the time the xbox2 comes out.
As for developers using sm3.0, I believe we'll see much more of it next year, after ATI support's it.