From gametrailers.com:
Here’s a short teaser for the game Assassin’s Creed 2 being developed by Ubisoft Montreal.
Not much detail, but still interesting!
 

From joystiq.com:
A trip to the high street may have resulted in an unexpected focus test for one of our tipsters, who says that he was shown very early footage of the next Assassin’s Creed. It apparently looked similar to the first game, though set around the 15th century — a few hundred years later. [...]