Taken from Ubisoft press release:

SAN FRANCISCO – April 16, 2009 – Today Ubisoft announced that Ubisoft Montreal is developing Assassin’s Creed II on all current-generation platforms for a scheduled Holiday 2009 release. The initial installment of Assassin’s Creed® was released in November 2007 to popular and critical success, selling 8 million copies worldwide and garnering awards such as Best Action Game 2007 from 1UP and Outstanding Achievement in Animation from the AIAS.