Google has posted an in-depth look at their click fraud detection scheme on their Inside AdWords blog, which says undetected click fraud constitutes only 0.02 percent of overall fraud in the AdSense network.
And in defense of these numbers, Google plans to release a new tool that will allow AdSense publishers to block specific users from seeing their ads.
Danny Sullivan wonders why Google waited until now to release the extra data. Could it be because Yahoo's Panama is suctioning off 3 to 5 percent of advertisers' budgets from Google? Avenue A clients, too, say Yahoo's new ad system is working just dandy.
Don Dodge provides a good recap of Google's cat-and-mouse game with click fraudsters.
At any rate, Google's basic message here is "trust us, we have it under control." It's doubtless that click fraud concerns have come up not only with publishers but also in meetings with concerned parties in new markets. Even though click fraud can't exist in the same manner in TV and radio markets, Google still has to prove the company is worthy of trust.
I would imagine that, as Google expands, these types of "trust us" posts will appear more often.