There seems to be a lot of talk about whether or not the PS3 version will be better. Well, that's really simple.
I used to say, Yes. PS3 will be better, however... I now don't give a rats ass.
So; Here's what I've gathered:
PS3 and 360's GTA IV won't differ, really. The graphics are reportedly akin to the brightness of Vice City, whereas the PS3 has a more realistic colour scheme like GTAIII. At the beginning of production, Microsoft reportedly bought the exclusive rights to certain downloadable content. However, with the PSN and all the downloadables via it, I'm sure PS3 will see different content in due / the same time. Or, when the exclusive licence runs out.
The PS3 controller is (in an unbias opinion) better. It's so damn sensitive! (though the R2 + L2 fucking suck ass... I hate that shape!)
We have rumours / news of online gameplay... Well, that right there goes in PS3's favour, since PlayStation users don't pay for internet like XBOXLiver's
That's about it, really.