Civilization IV and Warlords are on the list of eligible games. However, the list of award categories mentioned in the press release are only for FPS, RTS, and RPG. I asked them about it and they said they are including Civ4 in the RTS category.
The submission and nomination period started on May 29th, 2007 and will open until the end of the voting period, on July 16th. Voting will take place from July 2nd through July 16th, and the final award selection by industry judges will take place between July 16th and July 23rd. Final prizes and awards for winners will be announced on July 27th, 2007. More contest info can be found via the contest’s official site.