The update RAF does allow granting levels all the way to 81 (did this the other night, level 81 seems to be where the bonuses stop) but it stills follows the same rules otherwise. The granting character needs to be equal to or higher in level than the character being boosted and have enough granted levels available earned at 1 bonus level for every two levels gained. So a level 81 character could grant a level 41 character enough levels to hit 81.
So in order to grant bonus levels for a character to level 80 you would need the recruited account to be upgraded to Wrath and if you want to grant to 81 than Cataclysm.