Ahem. Xbox 360 fan/owner over here.
Just kidding, but I don't really know how much stuff can be packed into a Blu-ray disc? Maybe 7 kinds of dildos, 18 different SMGs, 574 total vehicles?
Oh yeah, the PS3 version will probably be held back. I don't think R* wants to work on 574 cars or 7 kinds of sex toys.
Would drifting be included in physics? That'd be innovative and fun....