A New Hope
This is sort of a new chapter in rakeback -- allowing existing accounts to receive it. Also recently there has been word that Full Tilt is allowing rakeback for existing accounts as well.
Rakeback came out of the Web site affiliate system, a way of rewarding people for signing up people to sites. It exists outside the poker world -- you can be an affiliate on Netflix, if you want.
Poker web sites give affiliates a percentage of the signee's rake. Some affiliates passed it on to the signees as an incentive to sign up with them.
Of course, rakeback is counterintuitive to a n00b, who often starts playing out of a desire to play, then starts chasing bonuses. By the time he or she hears about rakeback, he's already likely signed on to the site. So no rakeback for him.
Of course, Party didn't like the idea of players getting rakeback and really tried to cut the heart out of the practice earlier this year, threatening affiliates they would revoke their privileges if they allowed rakeback for signees. I'm glad the Web sites in the post-Party world differ.
Although I don't really play on Absolute, I'll probably go ahead and sign up for it, just in case I ever play there.