CEO and President of Gearbox Games, Randy Pitchford has stated that Gearbox will encourage players to mod their upcoming FPS/RPG crossover, Borderlands 2. Before you would-be modders can get too excited, though, he has also discouraged anyone from expecting them to release an Software Development Kit for the game. He adds that they had intent to provide the SDK for the first iteration of Borderlands but changed their minds because “…we found that most of what we would be able to do, was already accomplished by the gaming community.” Instead they allocated their resources to starting to work on Borderlands 2.
As a lack of a developement kit has not deterred modders from messing with the original Borderlands, expect the very active PC community to come up with their own toolsets to enhance Borderlands 2 to their desires.
(Via ThatVideoGameBlog)