On my i7 iMac with 10.6.5, 8GB RAM, Radeon 5750 GPU the game installs, runs and plays perfectly, have had zero issues with this one. I am, however, unable to set the graphics to high because it says my card doesn't support Full Screen AA, which is, I assume, a limitation on my part.
Well, the zombies cheat, maybe that'll be fixed in v9.3 :)