So far Ubisoft has focused all their Assassin's Creed-efforts on Assassin's Creed: Unity (in development for PC, PlayStation 4 and Xbox One) but they also have a last-gen game in the works for PlayStation 3 and Xbox 360.
The game, allegedly called Assassin's Creed: Comet, is said to be a sequel to last years Assassin's Creed IV: Black Flag, and during an investor meeting yesterday Ubisoft CEO Yves Guillemot stated that new information on this game is to be revealed shortly.
Based on the rumours Comet will put us in the role of an assassin called Shay, a sailor with a connection to the Templars (at least initially). The story is said to take place in New York in the year 1758, and important characters such as Haytham Kenway (Assassin's Creed III) and Adewalé (Assassin's Creed IV: Black Flag) will allegedly appear at some point in the story.
Assassin's Creed: Comet is expected to be released this fall, side by side with Assassin's Creed: Unity.
Cheers, CVG.