At least the pre Final Snow Leo Graphics update make Vmware Fusion stall (Vmware Panic in Log) be warned. I dont know if they or Fusion fixed that problem already. At least Nvidia GPUs had/have that problem!
My WoW BETA got VERY slow after this update. I actually had to dial it down from Ultra to High with my GeForce 8800 GT (3.2 8 core). Haven't tested SC2 yet, but will. I think it's encouraging that Apple is spending cycles trying to improve gaming. It is a huge reason why people buy their top end machines.
This update has caused me HUGE instability issues. First a scrambled screen on first startup. Then multiple hard freezes. Seems around AIM but I'm not 100% sure of the culprit yet. Be aware and don't install yet!