Apple seems to be consistently putting "Graphics" in their list of things to work on nowadays, so i expect there to be improvements with 10.6.5. Wishful thinking? Maybe. But based on their mention of Valve and Steam at the "Back to the Mac" event, it would seem they know that gaming has come back to the mac (pun not intended, but it works).
The next step is for apple to make a gaming computer. I think they could do it. It wouldn't be such a stretch. It would consist of a Mac Pro, minus the "pro" parts, in other words, no XEON, no ECC RAM, no fibre channel, etc.