You can check out the hands-on after the break -- after installing CrossOver Games, I first tried to load up Guild Wars using their installer's package interface, and was able to get it working pretty well. I then tried one of my favorite games, Civilization 4, and unfortunately, that one didn't turn out quite so well. And just for kicks, I also gave F.E.A.R. a shot -- it's not on CrossOver's compatibility list at all, but I've had a copy sitting around for a while that I haven't played yet, so I let the virtualization app take a crack at getting it working.
The hands-on is in this simple and easy-to-use (which is more than I can say about CrossOver Games) gallery format -- just click the picture furthest to the left down there and begin our journey into the exciting world of virtualization and game installation. I can tell you're excited already.
Update: Arjun found the problem with Civ in the comments; apparently only the Steam version is compatible. Which vibes with the rest of what I found: if you want to play any of the Steam or built-in games with CrossOver, they'll likely work just fine. But if you want to install another game from a CD (especially unsupported games), you're out of luck.