Originally Posted by Revs
The 360 was gonna have 256mb initially, but that soon changed their mind when they saw what the extra 256mb did to performance. I can't believe the PS3 gets away with 256mb.
Well, it's 512 shared which does add more flexibility but I'm not sure it's taht significant to 256 for system and 256 for video. I'd imagine you could program it so that the ram streams from system to gpu relatively easily. I believe the 360s 10mb of dedicated gpu(digitalfoundry mentions it frequently) ram helps the 360 a lot more than the unified architecture.