Gearbox Software Support now offers updated patch notes for a new version 1.1.3 update that's now available for Borderlands 2, Gearbox Software's role-playing shooter sequel (thanks nin). This addresses a couple of bugs and performance issues, and also adds an option to reset your challenge progress while retaining your badass rank:

Added the ability to reset all challenge progress for a character once they've completed 85% of all non-DLC, non-area-specific challenge levels. This will keep the player's current challenge bonuses and rank, but reset all challenge progress to 0 and allow challenges to be re-completed for additional ranks and bonuses. Resetting is available on the "challenges" screen of the status menu and will display as a tooltip at the bottom of the screen if the player has met the criteria.