In a recent Tweet via twitter Chris Jericho revealed that he recently did about 2 hours worth of voice overs for the game.
While full details are yet to be announced it is expected that he will have a storyline in the games RTW: Road To Wrestlemania, story mode.
Here is Jericho's Tweet
Just finished doing two hours of voiceovers for raw vs smackdown 2011. Maybe I'll try to actually play it next year.