Google's solution for Click Fraud ??

Wired carried an article by Schneier about the risk Google's revenues are facing due to Click Fraud. Schneier avers that Google's Cost-per-Action would be the right solution to Click Fraud.
Excerpt --

Google is testing a new advertising model to deal with click fraud: cost-per-action ads. Advertisers don't pay unless the customer performs a certain action: buys a product, fills out a survey, whatever. It's a hard model to make work -- Google would become more of a partner in the final sale instead of an indifferent displayer of advertising -- but it's the right security response to click fraud: Change the rules of the game so that click fraud doesn't matter.

That's how to solve a security problem.