Gearbox has released new details about an upcoming title update for Borderlands 2, which they plan to release shortly. The free update was discussed on a Gearbox forum post in which the developers stated that the update is set to offer plays with more inventory space.
A common complaint that players have right now is with the game's limited inventory space, which prevents many players from being able to hoard their weapons unless they create characters specifically for the purpose of using them as mules.
According to the post, players can expect to see "inventory/backup/storage increases" in the update. Likewise, the black market will also be expanded with the addition of more ammo SDUs (upgrades) along with Eridium maximums increased, so players will be able to do more with Eridium piles they have stocked up and upgrade their ammo count.
The update will be available for free to all players of the game and is expected to be released within the week. It is completely separate from three pieces of upcoming DLC which add a new Psycho character, a new story DLC, and a level cap raise respectively. The story DLC and the level cap raise will be a part of the game's Season DLC Pass, while the Psycho character will be sold separately.