How many messages did Google send about unnatural links?

At a search conference, someone said that earlier this year, Google sent out 700K warnings to websites about shady links. True? Not true? Matt Cutts, Bay Area, California Have a question? Ask it in our Webmaster Help Forum: groups.google.com Want your question to be answered on a video like this? Follow us on Twitter and look for an announcement when we take new questions: twitter.com More videos: www.youtube.com Webmaster Central Blog: googlewebmastercentral.blogspot.com Webmaster Central: www.google.com