Google hasn't confirmed that it rolled out a new Panda refresh, but signs point to one hitting on September 5th (Friday), according to Search Engine Roundtable and SEOs.
Barry Schwartz points to a post in the Google Webmaster Help forum from a webmaster whose site was hit, and shares a response he received from Google, which is standard Panda advice:
I'd recommend making sure your website has unique, compelling, and high-quality content of its own -- not just content from other websites.
He also points to a tweet from one SEO who says clients previously affected by Panda saw recoveries. Others in the comments on Schwartz's post seem to support the notion that such an update occurred. One suggests it began in the middle of August, and another said they had multiple clients seeing recoveries on September 6th and 7th.
Google doesn't really announce or confirm Panda updates/refreshes like it used to, as they happen much more frequently these days. Earlier this summer, they did confirm a major update, but typically, they're not going to be so noteworthy.
As usual, the guidance is to create high quality content.
Image via Wikimedia Commons