The word "exclusive" has been thrown around quite loosely as Sony and Microsoft promote their next-gen consoles. In most cases, it's believed that it will only be timed exclusives, available on a specific platform for a certain period of time before coming to all other systems.
In the case of Ubisoft's Assassin's Creed 4: Black Flag and Watch Dogs DLC for PlayStation 4 (and PS3), they will only be exclusive for six months.
In the latest PS4 trailer (spotted by Shack News), when Sony boasts about the games' exclusive content for the system, there is some small print at the bottom that reads "6 month exclusive." Neither Sony nor Ubisoft have commented on the timeframe, but it can be assumed that after this the content will be available on more than just PlayStation platforms.
As for the actual content, we already know what that entails. Black Flag players on Sony platforms will be granted access to three missions starring Aveline de Grandpré from last year's Vita title Assassin's Creed: Liberation. The content will total about one hour of gameplay and will "pick up a ways after her story in Liberation ends." Watch Dogs players, meanwhile, will offer PlayStation gamers four bonus missions that unlock an extra outfit for protagonist Aiden Pearce.
Assassin's Creed 4: Black Flag will be available for Xbox 360, PS3, Wii U, and PC on October 29. Xbox One and PS4 versions will be available at each console's respective launch. Watch Dogs, on the other hand, was delayed earlier this month and won't be released until 2014.
