Sega have registered the website domain www.dawnofwar3.com, presumably in advance of a new Space Channel 5 game announcement. OK, so it might well mean a sequel for Relic's muscular strategy game is on the cards—Company of Heroes 2 was a while ago, after all. Whois Lookup states that the domain was registered back in 2011 by Sega of America, and updated on March 26th of this year. Meanwhile, the registrant's email address appears to be that for Relic's IT department.
While Sega could just be registering the domain to protect it from squatters, a couple of years ago Relic did say that a new entry in the series was a "strong possibility". If you're wondering why you should be excited about a third Dawn of War, have a read of our retrospective of the original game.