He's signed on for a year through WrestleMania 29 next year!
And I'm calling it: Brock and Cena at WM29, but please do not make it the main event, like that boring Cena/Rock match at WM28.
They are probably trying to have Cena make the slow transition to heel, since being a face is not doing him any good. So losing to the Rock, and jobbing to Brock are big blows to his character. People just don't like that guy. I got no problem with Cena personally, but he is a boring wrestler, hence my feelings about the main event at WM28. I fell asleep on that match.
As for Brock, he should not have left the WWE in the first place, much less left with a bad taste in fans mouth at WM20.