I found out about this while watching a morning Bloomberg business news report. A class action lawsuit has been filed against Yahoo!, specifically that investors were misled and lied to about the quality of Yahoo!'s advertising business. There is mention of how ads were placed on sites that were not linked to relevance or queries; rather, they were placed on sites that users would visit by accident or were otherwise untargeted. (This sounds like ads that are placed on sites whose domain names are misspellings of popular sites, such as livejournall.com, and "dodgy partners" that are often sources of fraudulent clicks, topics that I have written about previously.)
The class period is given as April 8, 2004 - July 18, 2006. Former AV employees who were part of RIFs (reductions in force) around that time period might want to pay attention to this case, especially if they exercised their YHOO stock options during that period.