In an extensive interview with Attack of the Show's Blair Butler, Avengers writer Brian Michael Bendis confirms that Marvel's "Dark Reign" storyline will come to an end with a "big Marvel event" called Siege. It starts in December with a one-shot called Siege: The Cabal, which is followed in January by a four-issue Siege series.
Michael Lark will draw the Cabal one-shot, while Olivier Coipel will draw Siege. Both are written by Bendis. He says the storyline will bring a "seismic shift" in the Avengers titles on the level of what happened in Avengers: Disassembled and will reunite Thor, Iron Man and Captain America.
Siege was just one of several subjects Butler asked Bendis about; he also talked about Powers, various Marvel films, Fortune & Glory's 10th anniversary edition and much more. Check out the second part of the interview below (he talks about Siege at the very end) and go here to find the first half.
Also be sure to check out Dave Richards' interview with Bendis on Dark Avengers over on the main CBR site.