http://www.gametrailers.com/side-mission/2012/04/08/borderlands-2-will-probably-have-a-5th-playable-class-the-mechromancer/?utm_source=twitterfeed&utm_medium=twitter
Not guaranteed, but highly likely post-launch DLC 2ish months after launch (so Nov/Dec)
Should be right up Alyss alley... it's some lil cyborg girl who, I'm guessing, summons a robot you upgrade for her power.
What caught my attention most was that it's FREE.
good to see devs/pubs NOT trying to milk out every nickle they can