I do, more in thought than in practice (meaning: I play 1-2 games, yet my Steam Library is in the hundreds…). I do dual-boot for most games, even ones that have OS X versions… It's sad (and ridiculous) how much slower most of them are in OS X and I can't stand lowering the quality and still getting lower framerates when I have two 280x in crossfire… :\
PS: I spend 90% of my day in OS X and it's my OS of choice (by far). It's just not up to the task when it comes to raw hardware access performance…
I do, but I don't use OS X for games. For me, gaming and over clock works better on Windows. Besides, I only use OS X for work purpose (Graphic Design), although I noticed that adobe software runs a bit faster on windows.
i play Left for Dead and Left for Dead 2 in steam in OSX also Call of Duty from the app store also Need for Speed Most wanted and Truck Simulator never hardly use windows i don't even have windows on a partition on both of my hacks just OSX