Ubisoft is doing a bang-up job of keeping this here Assassin's Creed 4: Black Flag under wraps, aren't they? A countdown page appears to have given away the game's release date, shortly after packshot leakage obliged the publisher to confirm its existence ahead of schedule. The big day is 29th October 2013 - and according to some accompanying text, Black Flag is "also coming to next-gen consoles".
The new story takes place in and around the Caribbean in 1715, reportedly, and stars Edward Kenway, pirate and obsessive flintlock pistol collector. He's Haytham Kenway's daddy, don't you know. AllGamesBeta has dug up a "trailer still" of some vagabond with a beard and fancy earrings. Could be related.
Update: Ubisoft has announced the Assassin's Creed 4: Black Flag release date - it's launching in the UK on 1st November, for both current and next generation consoles.