Obsessable is optimistic. The site managed to get Warhammer Online up and running in XP via Boot Camp, and the results were impressive, with no graphical hang-ups and only a little bit of installation trouble.
OK, so it's not exactly Alienware and WAR isn't exactly Crysis. But it's definitely a step in the right direction. If you need to see Apple and gaming fused with your own eyes, there are a couple of videos right here.