It's a happy day. I was considering installing Windows so I could dual boot on my Arch machine but this has made me reconsider. I remember how years ago, on KDE2, wine barely ran anything and the best games available on *nix were things like NetHack. What a long way it's come! Now we have a prominent gaming platform and ports of some excellent premium games. Things like this are edging GNU/Linux towards mainstream success on the desktop.
I think that one thing which would help here is a more complete gaming API ala DirectX. We can already achieve this with OpenGL/SDL/OpenAL/whatever good networking libraries there are but a project which aggregates these into one would be beneficial, in my opinion.