The news comes courtesy of Peter Berg, who let the news slip today while at the Toronto Film Festival. "Everybody's going to come back for a sequel." However, Sony stressed that none of the talent has been officially signed.
Berg also revealed some of the secret plot details -- and here we venture into spoiler territory for Hancock, so look away if you want. Theron and Smith will reprise their roles as "immortal gods," who lose their powers when they hang around each other for too long. Nevertheless, they must pair up to destroy a third "entity," which I'm guessing is either some kind of alien or another god. The movie will also explore their 3,000 year old home world which was only hinted at in the first film. Bateman will play the humble PR executive, though I wouldn't be surprised if he's revealed to have some kind of superpower at the end! No release date for Hancock 2 has been set, and the film is still in the early writing stage, but I bet you'll see this kick off just in time to compete with the next slate of Marvel films.