There's been rumours around, but it's finally been confirmed in our old comrades at the PC Gamer* podcast. Talking about their forthcoming issue where they reveal that the first Dawn of War 2 add-on pack will feature chaos. And it's called Chaos Rising. It's welcome, but not exactly an enormous surprise - I thought Chaos would be one of the most-likely factions to be in the original game. There's little more in the podcast - expect more to come when the subs copies arrive with their readers shortly.
*UK. As in, the original one. Yeah, you heard.