So apparently the new class is released today (a full week ahead of schedule). This new class works in a similar way to the Commando's turret - in the fact that you get a robot companion that follows you around and kills stuff. Looks interesting.
I am too committed to my Commando and Assassin at the moment but that will definitely be the next class I play
Check out here
for information on the announcement and here
for the Mechromancer Twitter page.
Lastly, check out here
for the complete skilltree of this new class!