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.