most of the games on 360 are upscaled i can notice the difference, but it doesnt hinder my experience of the games.
If u want to try out ps3 games at full 1080p non-upscaled i recommend Lair its such a beautiful game graphically at true 1080p i was blown away, but gameplay not so much. or u could try wipeout HD very crisp lines silky smooth frame rate. or GT: Prologue the cars look almost real!
I plan on buying planet earth on blu-ray, i dont own any blu-rays yet, but having stuff in true 1080p is surreal