Adsense To Offer CPA

Darren mentions that Google have launched the beta of a new addition to Adsense – AdSense referrals (beta)
Unlike “normal” adsense, you don’t get paid per impression or per click. You only get paid based on actions defined by the advertiser (where’s the adwords end of this to see what the setup is?)
Hopefully this won’t become one of those endless betas like the Adsense for RSS / Feeds that seems to have vanished, as it could be a very interesting addition to people’s arsenal.
EDIT: There’s also a post on the official Adsense blog