Assassin's Creed II follow up Brotherhood will be released in November.
The date has been revealed in an E3 trailer for the game, which says the title is released in the US on November 16th. The trailer is embedded below.
The European date can't be much different - the last two games have had near-simultaneous global launches.
Assassin's Creed Brotherhood is the third game in the series, but not explicity Assassin's Creed III - instead Brotherhood is a continuation of the second game's story, but also features online multiplayer and a new line-up of hero assassin characters.