Sierra/Vivendi plans to close 21 game servers on 1st November. The Sierra site gave no reason for the closures; it could be something to do with the Activision Blizzard merger, or just be because these games are knocking on a bit now.
The following game servers will be shut down as of 11/01/08: Alien vs Predator 2, Arcanum, Caesar IV, Dark Reign 2, Emperor: Rise of the Middle Kingdom, Empire Earth, Empire Earth 2, Empire Earth: Age of Conquest, Ground Control, Ground Control 2, Homeworld, Homeworld: Cataclysm, Nolf2, Red Baron, Sanity, Star Trek: Armada, SWAT3: EE, SWAT3: GOTY, The Incredible Machine, Tribes 2, Vampire. More info here.