Google is always working to improve search engine by making search more relevant.
Google has announced on Twitter, Sept 18 2012 that they pushed out a Panda refresh stating “Fewer than 0.7% of queries noticeably affected”
The previous Panda refresh was on August 20, 2012 and labeled 3.9.1.
Get the latest Google Panda, Penguin Algorithm update at SEOMOZ Latest Google Panda, Penguin Algorithm Changes.