The title of the third DLC pack for Borderlands 2 seems to be "Sir Hammerlock's Big Game Hunt." The news comes from data mined PlayStation 3 files pulled from a recent update, according to a Gearbox forum post. In addition to the DLC's title, three PS3 Trophies are revealed as well, awarded for completing the mission "The Fall of Nakayama," compleing all Hammerlock's hunt side quests, and discovering all of the new named locations.
There haven't been any announcements from 2K Games or Gearbox regarding the third Borderlands 2 DLC, though two content drops are still coming before June 2013 under the terms of the game's Season Pass. In a statement, 2K re-confirmed that two more DLC packs are still incoming, adding that "we are really looking forward to sharing news about our third add-on campaign and other downloadable content soon."