CPA, Cost-Per-Action, As Click Fraud Solution?

Last month, Putting an End to Click Fraud at iMedia Connection had Ron Belanger pushing the idea that CPA -- cost per action -- pricing for ads might help solve click fraud issues. Why? You'd only pay for traffic that converts. This month, Why CPA is Not a Cure for Click Fraud has Isaac Scarborough at iMedia delivering the counterpoint. Actually, he sees a lot of positives but not a complete end to click fraud, plus difficulties in moving people used to CPC to CPA.