Google Panda 2.5 13th Oct
Athough Matt Cutts only mention heavily Ads related site may be penalize on the recent Pubcon. There has been rumours that the algorithm change already took place , specifically on 13th of October 2011. One of our heavy ads website has been penalize by Google from the algorithm change thought having unique and quality content on it.
There has also been reports of heavy traffic losses from bloggers and webmasters after the 13th of October. There has been confirmation from Google side on Panda 2.5 implementation on 13th of October although not much information was released from Google.
If traffic to your website was effected seriously it is advisable to remove more Google Adsense ads from you website.