Okay so you should be keeping a track of this if you are a fan of the Warhammer franchise and especially Dawn of War series.
A domain for Dawn of War 3 was registered by Sega of America and you can look it up on WhoIs right now.
Firstly if you are confused, Sega of America is the parent company of Relic Entertainment i.e. the developers of both Warhammer 40,000: Dawn of War and Warhammer 40,000: Dawn of War II.
So does this mean they are working on the sequel? Maybe not right now, but I am sure it means this is going to be a project high on their agenda soon.
It has now been over six years since Warhammer 40,000: Dawn of War II was released. The game had received largely positive reviews from critics and gamers alike. The last time developers visited the series was with the Retribution expansion pack four years ago.
In the last couple of years Relic Games has been rather busy with Company of Heroes 2, Company of Heroes 2: The Western Front Armies and Company of Heroes 2: Ardennes Assault.
So, saying that Warhammer 40,000: Dawn of War 3 is definitely in the works, on the basis of just the domain registration would be jumping to a conclusion a lot earlier.
It could be that Sega of America just wished to ensure that the domain was owned by them just in case they decided to make the game sometime in the future.
In short, we will have to wait for an official word on Dawn of War 3.