Well, everyone is running around like chickens with their heads cut off checking their web analytics and webmaster tools to see if their website has been hit by Google Panda 4.0 update or in strong recovery mode.
In a tweet from Matt Cutts over the weekend, it is official that Google started rolling out the Panda 4.0 update.
If you own and operate a website and been keeping tabs on SEO in general, then you know that search marketing has changed quite drastically with the latest Panda and Penguin updates over the last few years.