GTAIV: PS3 version runs at 630p while 360 version at 720p

[Kushan]

Well that depends. There's a possibility there's a known rare glitch that's documented that R* just happened to miss, so in that case it would be R*'s fault. However it's just as possible that the glitch ISN'T known and that Sony/Microsoft did something differently enough that the same code would act differently one 2 different machines.

It could also be a variable we haven't seen yet, like perhaps the game does something different for a certain region, or when a certain amount of HDD space is free, in that case it really IS R*'s fault, but we have absolutely no way of knowing. R* know their code better than anyone else, though and no doubt Sony/Microsoft will be helping them fix it ASAP since it really is the biggest game of the year.