The Mechromancer, named Gaige, is the fifth playable class in Borderlands 2. It was first revealed at PAX East 2012, the class was added as post-release downloadable content and is set to release today. 2K games released a new trailer for this downloadable content.
Borderlands 2 was released on September 18 for all major platforms. There will be at least 4 packs of downloadable contents for Borderlands 2 according to 2K games announcement earlier this year. All packs will be available before June 2013.