Hot on the heels of the inFAMOUS 2 release is news that its developer, Sucker Punch, is working on a new PS3 title. They've posted a job listing on Gamasutra looking for a senior producer for this unnamed game. This full-time gig is going to be for a big game as they're looking for five years experience, with at least one AAA title under the applicant's belt as a senior producer.
The only information this post gives is that the game will be on PS3. inFAMOUS 3 is the obvious pick. I'm sure that would be good, but Sucker Punch is super-talented, and I'd like to see them try something completely new.