During Comic-Con, which took place yesterday in San Diego, Activision comfirmed the development of Marvel Ultimate Alliance II: Fusion. Which is scheduled for PS3, Wii and X360, the game is currently in production at Vicarious Visions studios . No other information was given to us, sadly, but if you pick up the latest issue of GameInformer there should be more details in their Marvel Ultimate Alliance II article.
Ummmm yea this is old news cause E3 was last week and they showed a trailer for the game then. so i would say that was official enough for me