Spiffy Mac Gaming Universal Binary Matrix
Admittedly, the gaming arena for the Mac platform isn't nearly as large as that of the PC platform, but neither is it non-existant. And many, including myself, expect the Mac gaming market to grow with Apple's move to Intel chips, as it should make easier the task of porting games from the PC platform. And so it's interesting to watch the existing Mac games on the market get translated to universal binaries. MacRumors has a spiffy porting chart they are updating as games get translated.
My brief experience with my new 20" Intel iMac (256MB video card) has shown that gaming performance has improved significantly with every universal binary game I've tried; UT2004, World of Warcraft, and Doom 3 have all scored significantly higher framerates than on my Dual 2.0Ghz G5 tower (64MB video card). I'm sure that some of this is the faster/better video card, but I believe it's also because the Intel chips are just faster.