Google said this freshen began commenced rolling out on 8 June 2012, Friday and has an result of less than 1% of search queries in the U.S and about 1% worldwide.
Danny Sullivan Said, the search forums took observe to major changes in the search results, specifically impacting sites that were originally shoot by the Panda update. I reached out to Google this morning for verification and they have confirmed the update.
On April 27th Google has released out Panda 3.6, about six weeks before this update. Google launch to do Panda as well Penguin freshen every one to two months.