It appears more Assassin's Creed is on the way, though it's impossible to tell just what it could be. A logo for "Assassin's Creed: Rising Phoenix" was purportedly leaked, raising the obvious question: what the heck is it?
The logo surfaced on All Games Beta (via IGN). The watermark in the bottom corner indicates it's from Ubisoft Digital Arts, the company's "cinema creation studio." That would point towards a film project, rather than a game, but it's just as possible that this is another game in addition to Black Flag.
Shacknews has contacted Ubisoft regarding the image, and will update as more information becomes available.