I just purchased this game through Steam this week and love it! I hope there's a Mac OS X version in the works, this game would be fantastic on the Mac. Right now I'm using other methods (Boot Camp) to play the game, it would be great if a port is available in the future.
It actually kind of runs right now using Crossover/Wine (but on top of Steam, which adds significant overhead to the emulation), with annoying graphical glitches in the window drawing and menu system - but the main game works if you can get to it. But I'd still love to see a native Mac version.