There's not gonna by any cross platform online play. Microsoft tried it with a 1st party game(Shadownrun) and it flopped big time. They have to gimp the PC version otherwise they'd slaughter console players because of the precision of mouse and keyboard, and no company wants to do this. And not all PS3 games are server based, COD4 on PS3 is actually P2P like 360. So far its been mostly 1st party sony games that have put up servers, i.e Warhawk, Resistance.