Click fraud is threatening to kill Google’s biggest revenue stream, AdSense. It’s becoming an ever-increasing problem and although Google has been battling the problem, so has the RIAA been battling music piracy for years – our point is that hackers, fraudsters and criminals in general always find new ways of working their way around the system. So I don’t think Google will be able to stop this and that means that the lawsuits against the company (due to advertisers losing a lot of advertising money for no benefit) will just continue to come.

Apparently however Google is considering to evolve to a CPA (Cost-per-action) advertising system, whereby an advertiser will only be charged if the user completes an action ie. fill out a form, survey or request a quote. This changes the whole AdSense concept at current and it might change the whole online advertising system that Google have build over the past few years. More here.