Google's PPA Test

Google recently announced that they have launched a Pay Per Action (PPA) beta. Most of Google's revenue comes from their Pay Per Click (PPC) model. Google therefore must have analyzed how the PPA model would affect their ad revenues.
Advertisers are not concerned about how much they pay per click, they do however care about how much they pay per action. An action can be defined as a lead, a sale, a pageview, etc. Most large advertisers already track the cost per action (CPA) and use optimization software or services to hit their CPA goals.
Google's PPA model will therefore affect a number of middlemen, including companies that specialize in lead generation. Google's PPA model will also impact Google's revenue in the short term. The PPA model serves to reduce inefficiencies in PPC model. However, over the long term Google is assuring advertisers that they can bid for only for revenue events that effect them and let Google manage the rest.
For now, this beta is only on Google's Content network (not on Google search). This will help advertisers concerned about click fraud on the content network.
Overall, the announcement is a positive step, one just wonders when Google will roll it out as a broader program and how it will affect Google's revenue.