Currently ,the ports of X360 games in the PS3 only use the PPE and the RSX ,some use a SPE to optimize some graphic effects but little more .Even only using the PPE and the RSX the games look nearly identical .Some have little problems (frame rate issues in determinate stages ,some graphic filters bad ported because not modified ) and some look better (NBA 2K 7,Fight Night 3 ,Oblivion) but they keep the pace with the best the X360 is offering right now .The PS3 even if it doesnt lead will benefit from all the occidental games in the market as making a port from X360 isnt so difficult .
What would be interesting would be to see a PS3 game using fully the Cell ,the RSX and the BLu Ray storage for massive content and tons of graphic information .Now I would like to see that "ported " to the X360 .
