Guys, can I make a final suggestion? Don't argue about games that aren't out - it's meaningless.
Forza 3 looks great so far, so does GT5 - which is quantitively better cannot be meaningfully argued until they are both out and in your hands. Otherwise you're using screenshots, videos, etc. made for other purposes, without common framework for their generation, etc. or extrapolating from marketing material.
Both are sure to look great and be good. Both will make their consoles shine because, as I pointed out myself earlier, both are built from the ground up specifically for that console. IMHO no multi-platform title (unless superbly coded) will equal a superb exclusive game on a console specific engine.
If Uncharted and KZ2 seem to slightly edge titles on 360 its because both are on exclusive engines - whereas most great 360 FPS/TPS are on non-specific engines. On the other hand 360 supports non-specific engines better, for the most part (or at least more easily).
Relax - its Sunday! Chill! Actually, I'm going to take my own advice and bring this little surfing session to an end and go play something!
Try to be reasonable... its easier than you think...