According to Click Forensics, the last quarter of 2008 saw a significant increase in the amount of fraudulent clicks, up to 17.1%, as opposed to 16% from the previous quarter. You can compare this to three years ago, when the rate was closer to 14%, and under 10% in 2005. There was also an increase in the amount of automated fraud through the use of botnets, which now account for a third of faked traffic.
Neither the companies providing the services or the businesses buying advertising are doing anything wrong, but a resolution will ultimately have to come from the search giants. Luckily for those involved, Google and Yahoo have both gotten better at ensuring that people are not charged for the fake traffic.