An anonymous reader writes
"Wired reports that Google is making some effort to put a crack in the practice of click-fraud. Because of the pernicious abuse of the company's advertising business, it simply can't be sure that anyone is actually looking at the ads. Bruce Schneier talks about the problems of ensuring that people are really people, and Google's solution." From the article: "Google is testing a new advertising model to deal with click fraud: cost-per-action ads. Advertisers don't pay unless the customer performs a certain action: buys a product, fills out a survey, whatever. It's a hard model to make work — Google would become more of a partner in the final sale instead of an indifferent displayer of advertising — but it's the right security response to click fraud: Change the rules of the game so that click fraud doesn't matter."