I think my point has been missed here - I don't doubt that those performing slef upgrades have seen the jump.
So I'll simply pose the question again: has anyone purchased the base model (120gb HD) on a BTO from Apple with at least 2gb and found 256 VRAM in the system info?
This has been beaten to death. If you have 1 gb you get 128 mb vRAM. If you upgrade to 2 gb or more you get 256 mb vRAM.