Yeah, they announced this back at E3
http://mma.easports.com/home.action
Fedor Emelianenko - Confirmed by Benji Radach & press release mixfight.ru
Randy Couture - Confirmed by Benji Radach & Tim Sylvia
Tim Sylvia - Announced in interview
Gegard Mousasi - Press release distributed by mixfight.ru
'Babalu' Sobral - Thanked EA Sports MMA among his sponsors
Benji Radach - Announced in interview
Tim Kennedy - According to ArmyTimes
'King' Mo Lawal - Announced on MMA Live
Frank Shamrock(not confirmed) - Has been helping with the game.