Ultimate Vault Hunter Pack ($5, included in Season Pass): Includes a new tier of weapons (Pearlescent), level cap increased to 61, and Ultimate Vault Hunter Mode, aka Playthrough 3.
DLC releases April 2nd
The new vault hunter is a giant psycho named Krieg
Psycho class has abilities that have been seen in the game in enemies, "negatives can be positive", high-risk; high-reward gameplay style Action skill: melee smash with giant Buzz Axe Rampage, ranged throw giant axe
Each kill completely restores Krieg's health
Skill trees:
Bloodlust: kill skills, accumulate stacks by dealing any type of damage
Mania: high-risk, high-reward; taking damage powers up your action skill (ex one skill enables friendly fire)
Hellborn: Having an elemental effect is beneficial (eg on fire = more damage)
Instead of FFYL, Krieg has "Light the Fuse". instead of shooting you throw sticks of dynamite and can revive by killing with explosions
A new "Diamond" edition Loot Chest is releasing in May 2013. It includes a redesigned loot chest case, certificate of authenticity (5000), the 4 main characters wanted posters, window decals of all the gun manufacturers, a Goliath Mask replica and a shift code to unlock a goliath mask head customization, and a deck of 20 stat cards for different legendary weapons (and shift codes to get all of those guns)
Krieg the Psycho will cost $10, those at the panel got it for free :(
Krieg releases in May
A teaser trailer for the 4th DLC was shown, it was Mordecai, Brick, Lilith, and Tina playing "Bunkers & Badassess" (D&D), mentioned something about "passing the time while the vault hunters beat down that hyperion informant downstairs"
(Credit for this info goes to TheRealMe99 from reddit)