Advertisers are reported to be very interested in the new AdWords PPA (Pay Per Action) program as Google began beta testing PPA. Pay Per Action is billed as click fraud killer because advertiser pays only when a predetermined conversion has taken place, very similar to affiliate program really.
In a response to questions advertisers has been asking Google PPA team, it becomes clear that only US advertisers may use PPA at present and the option to pay a percentage of the value of the transaction like some of the advertisers requested is now available. Advertisers will have to pay a fix cost per action.