Ubisoft's media sites unveiled Assassin's Creed III earlier this week. They reported that Ubisoft has been working on this title for three years now. A release date of October 30th, 2012, is already in place.
Original release info from Game Informer.
An interesting take by Now Gamer.
February 29: Kotaku article showing possibly leaked image of the new assassin.
March 1: GameInformer March cover set to feature Assassin's Creed III and box art reveal.
March 5: Reveal Trailer
June 8: "Frontier" Gameplay (Commentary version)
"Naval Warfare" Gameplay
June 13: Assassin's Creed III Liberation, a full title for the PSVita, also set during the revolution, featuring a female protagonist.
July 2: Four new Videos! (Including Assassin's Creed III Liberation Trailer):
4th of July Trailer
Official E3 Cinematic Trailer (My personal favorite)
Marketplac Massacre Gameplay Video
August 23: Inside Assassin's Creed 3 (Four part making-of series):
September 6: New TV Trailer
October 4: PS3 players will get an exclusive one hour DLC for AC3, and all consoles will get The Tyranny of King George DLC. There will also be a season pass available that will include all the DLC for AC3 for a discount.
Newest trailer: Connor Story Trailer showing how he becomes an Assassin.
October 17: IGN's Making of Assassin's Creed III:
October 23: Assassin's Creed III interactive trailer.
October 29: Final Launch Trailer
Updates to follow.