I downloaded the Steam Mac version and out of 40+ games, 1 was available for the Mac (Portal). As my PC is my main gaming platform, I doubt I'll buy games based on whether they are available for the Mac or not.
Especially when as soon as I have time, this iMac will have 7 installed on it instead. I gave it a few months, unfortunately OSX just doesn't cut it for they way I use computers. I really tried to like/get used to it, but it's just so, I dunno, 'bleh' is about as descriptive as I can get at the moment