Google has confirmed they have pushed out a refresh on the Panda algorithm on Friday, April 27th.
I noticed an uptick in Webmaster discussion around Google changes over the weekend, mostly at WebmasterWorld and asked Google to confirm if there was an update. Google confirmed they refreshed the Panda update on the 27th, but it was a limited update not affecting that many sites.
This was an unusual update being that Panda 3.5 was released on April 19th, making a 8 day gap between 3.5 and this update, 3.6. Typically Google pushes out a refresh of Panda every 6 weeks or so.
A Google Spokesperson said:
We’re continuing to iterate on our Panda algorithm as part of our commitment to returning high-quality sites to Google users. This most recent update is one of the over 500 changes we make to our ranking algorithms each year.