Update: Gearbox Software president Randy Pitchford confirmed via Twitter the download content is hitting a week earlier. It now releases Tuesday, October 9 on all platforms. Pitchford says it should be available to download by the end of the day.
Original Story: Gearbox Software confirmed the upcoming download content Mechromancer is coming October 16 for $ 10 or 800 Microsoft Points. The Mechromancer content is available for free if you pre-order the game. Gearbox said it plans to release four additional DLC content for Borderlands 2 that can be purchased individually or part of a Season Pass.
Borderlands 2 is out September 18.