Borderlands 2 is titled 'Captain Scarlett and her Pirate's Booty', according to the game's updated trophy list. PS3Trophies noticed three extra Captain Scarlett trophies added to the game via yesterday's title update.
The three trophies are for completing the "X Marks the Spot" mission, discovering all named locations in Oasis and the surrounding Pirate's Booty areas, and completing all Pirate's Booty side missions. This, along with information drawn from the game's PC source files by Gearbox forum users, suggests the DLC introduces new areas.
We've reached out to Gearbox for further information on the DLC, and we'll update you as soon as we know more. Until then, this was the voice of the Mysterons, and as ever we know that you can hear us.