The ongoing WebmasterWorld thread has been tracking Google updates and several SEOs there believe that Google is doing a Panda refresh, which would take us to Panda version 3.7.
Google has not confirmed a Panda refresh.
The last Panda refresh was Panda 3.6 on April 27th so we are due a new Panda refresh any time now.
Also note, we had our first Penguin refresh last Friday night / Saturday morning.
One senior member at WebmasterWorld said:

I do see some changes today. One odd one is in the financial sector, shortly after Penguin was released, many observed the website about mold/fungus ranking top 10 because it had hidden links in the footer. The website was removed from ranking. The owner has since removed the links and now that website has absolutely nothing to do with anything financial -- but it's ranking again on those terms. Another site I monitor has dropped further on key phrases (over 200 spots).

Others reported other fluctuations in the search results and claiming it looks like Panda.
Past Panda Updates:

• Panda 3.6 on April 27th
• Panda 3.5 on April 19th
• Panda 3.4 on March 23rd
• Panda 3.3 on about February 26th
• Panda 3.2 on about January 15th
• Panda 3.1 on November 18th
• Panda 2.5.3 on October 19/20th
• Panda 2.5.2 on October 13th
• Panda 2.5.1 on October 9th
• Panda 2.5 on September 28th
• Panda 2.4 in August
• Panda 2.3 on around July 22nd.
• Panda 2.2 on June 18th or so.
• Panda 2.1 on May 9th or so.
• Panda 2.0 on April 11th or so.
• Panda 1.0 on February 24th

I will try to get confirmation on this possible Panda refresh and update this story and post a new one on Search Engine Land, if Google confirms it.

Source: webpronews