This Wired News article has a summary of last week's panel on click fraud at SES.
"Search engines don't have the incentive but have the data, while the advertisers have the incentive but not the data."
So if 33% of the audience has received a refund check, does that make it a big deal? I wonder if it's still 'under the radar' because the businesses are willing to put up with it at the current level? Too busy to fight. I wonder when that will change?