Sure, concerns are rising about clickfraud -- but do we even know how to define what a fraudulent click is? ClickZ gets Google and Overture to provide their own definitions in Google and Overture Define Click Fraud. Overture goes basically with calling it any click not done in "good faith," while Google leans towards clickfraud involving artificial or malicious clicks.
And hey, is it "clickfraud" or "click fraud?" I'm sticking with the single word for now, while ClickZ goes with two words. I asked our regular presenter on the subject at our SES shows Jessie Stricchiola which she favored. Two words, she replied. Hmm -- maybe I'll have to change my mind!
For more on the subject of clickfraud, see the Search Ads: Clickfraud of our Search Topics area available to Search Engine Watch members, which summarizes stories on the topic going back for years. FYI, here's one of the earliest we list, from Wired in 2001: Spam Scam Targets GoTo Listings.