lol @ vid. The most advanced game I've ever played on a mac was at my uncle's house when I was 15 or so.
I've seen my brother play Age of Empires III and Football Manager 2009 on his macbook though, so I guess there are still some games worth a shit on the mac. As for mac gamers...Macs use intel chipset these days, and I'm told that already makes a huge difference in porting titles and/or developing for both platforms. So I suppose it makes perfect sense for Valve (and others) to jump on the mac gaming market. Valve's portfolio alone could be enough to spark a 'gaming revolution' for the Mac.
Otoh I'm sceptic - isn't the point of people who own macs that they don't play games?* Unless you have the money to spare to buy a mac next to a PC, no gamer in his right mind would buy a mac. But maybe they're gambling on it that PC gamers secretly always wanted a mac but couldn't because of their gaming habit. I find that...unrealistic.
*In my experience, macs are predominantly present in the airhead American trust fund students who spend their day in coffeeshops looking interesting. In Prague in particular this was the case.
) The only games I know of that are on Mac are Sims and Football Manager. Oh, and WoW.