It wasn't supposed to happen but the trailer for "Assassins Creed IV: Black Flag" was leaked today. Apparently the video was on IGN but then it was promptly taken down.
The trailer gives a brief glimpse of the newest hero of the "Assassins Creed" universe, Captain Edward Kenway, father to Haytham Kenway in "Assassins Creed III". He is everything you would expect of a pirate captain: debonair, vicious and without mercy for his enemies. In one scene it shows Edward slowly approaching a target, stabbing the target and then walking off with his girlfriend. I can imagine Ezio from "Assassins Creed II" doing such a thing but Altair and Connor would look awkward to say the least.
Anyway, make sure to go to All Games Beta to view the video.