As a render artist, I can tell you that the Nature demo is FAR ahead of anything on current consoles, in terms of quality and technologies used. It has a massive amount of polygons, tessellation, global illumination, dynamic fluids physics and the texture size is brutal compared to anything the PS3 and the 360 have done.
Also, as a computer hardware aficionado, I'm starting to think that a R700 GPU is not enough to give the detail and performance seen on that demo. Might as well be a R800 GPU, with OpenGL 4.1.