Assassin's Creed 4 may be Assassin's Creed 4: Black Flag, a piratey escapade featuring cutlasses and scary bearded men and much talk of rigging. We deduce this from retail materials circulated by Kotaku. There's also a rather dubious looking screenshot, care of the Examiner.
According to the latter, the game's main character is Edward Kenway - father of Haytham. He's described as "a privateer, assassin and occasional pirate". Black Flag allegedly takes place in and around the Caribbean isles of Jamaica, Cuba and the Bahamas. Perhaps we'll meet Jack Sparrow, eh?
More as we get it.