A lone voice, crying in the wilderness:
"What is the definition of click fraud?"
Google just released a new feature that shows advertisers the percent of invalid clicks they've received. What's the criteria for that?
A few ideas: bots, India-based competition-smashing companies, high-school kids researching topics for school papers, Firefox extensions that pre-download pages for you, greasemonkey scripts, people whose browsers or connections timeout after they've clicked, curious competitors who click on your ads to see what the landing pages look like...
Without a clear definition, I have to view Google's 'feature' as nothing more than a flimsy PR stunt. And I don't think the problem will be solved until we come up with a definition that ties into conversion rates -- which just shifts the problem to a different issue.