GOG doesn't sell any mac compatible game for now.

How does it fare on Mac OSX with Wine? It works nicely with Wine on Linux.

It works perfectly in Wine. Just get Wineskin, make a 1.4.1 wrapper (other Wine versions work as well) and install it. I didn't need any Winetricks or overrides. One thing to mention, I'm using the international retail version, so when the installer asked me if I want to install DirectX I declined. I don't know about the GoG installer, but I doubt that it makes a difference.

The Steam Windows version worked perfectly for me in CrossOver 11 on my Core Duo GMA 950 MacBook running 10.6.8 (with the 2008 Visual C++ Executable and the DX9 installers already run during my initial installation of Steam) – the Mac port has roughly double the system requirements of the Windows version, which is why I choose to run it in WINE instead of natively.

The GOG version works well under Wineskin with WINE 1.5.10, though I prefer to run it under 1.5.8 as fullscreen and resolution switching don't seem to work properly with 1.5.9 and 1.5.10. I did install vc2008 and d3dx9 through Winetricks just to be on the safe side.

Now that GOG has Mac games, is there a chance of the Mac port coming to GOG?