A new update for Borderlands 2 will begin rolling out on April 2.
This update contains the new Ultimate Vault Hunter Mode and more storage space along with a variety of bug fixes. These include some changes that were previously available as hot fixes.
Exact details on the update for each platform can be found below:
PC Update Information
Xbox 360 Update Information
PlayStation 3 Update Information
Also available beginning April 2 will be the Ultimate Vault Hunter Upgrade Pack which allows characters to gain 11 additional levels and skill points as well as pick up new Pearlescent-tier weapons and "Ancient" E-Tech relics.
Exactly when the update and Ultimate Vault Hunter Upgrade Pack will begin rolling out depends on the platform, region and the timing of that particular service.