I'm honestly surprised this hasn't made the front page.
In short, Gamespy's new owners have decided to start shutting down lots and lots of older MP servers with no warning whatsoever. Titles impacted include SotS1 (you can still do direct IP connect, thank goodness), Sniper Elite, both Neverwinter Nights, Microsoft Flight Simulator X, Swat 4 (dammit!), Hidden and Dangerous 2, Wings of War, Star Wars: Battlefront.
This is why every game needs a direct IP multiplayer option, you never know how long any service is going to be around, or continue supporting their older titles.