[Update: Gearbox Software hit us up to clarify a point on this article. The Mechromancer content will be available 60-90 days following the release of Borderlands 2 and will be free only to those players who pre-order the game. We're sorry for the confusion! -Z]
At a PAX East panel, Gearbox President Randy Pitchford revealed information about a fifth playable character class which will be available as post-launch DLC for Borderlands 2. The "Mechromancer" character, currently in a concept stage while the team focuses on finishing the core game, was depicted in a slide as a young, redheaded girl sporting pigtails, goggles and a robotic arm. The class' abilities include controlling robot companions, including one referred to as "Deathtrap."
The content, "doesn't exist yet," according to Pitchford, but that the team plans to add the class as post-launch DLC, arriving some months following the release of the game in September. Pitchford also confirmed that this content will be free.