A senior Google executive has reportedly shared that the company is
making moves towards cost-per-action (CPA) as a more ideal
auction-based pricing model.
According to Marissa Mayer, Google’s VP of search product and user experience,
the quest culminates in "the Holy Grail" of CPA. However, she admitted that goal
was a long way away, the company is in fact already testing a version through
its AdWords product.