Its possible, but not easy. A friend of mine got Supreme Commander: Forged Alliance working on it but it was a pain. He had to find video drivers that worked for it and there were a few other issues as well.
Originally Posted by Isellion
Sorry for resurrecting this thread, but the two posts above are wrong. I'm running Server 2008 R2, and it plays games without any problems whatsoever. You have to tweak things a little, but it takes 10 minutes, tops. Check out this guide, I followed that when I installed and Server 2008 R2 has been working great since. No problems at all. I've been playing TF2, L4D2, Half-Life 2 (including FakeFactory's mod), and Plants vs. Zombies. That site has a very long list of games that people have tried with 2008 R2, and very few of them seem to have any problems. Hope this helps!