Google announced that a data refresh is rolling out for Panda, and that webmasters should expect "some flux" over the next few days. Here's a tweet Google just posted:
Panda refresh is rolling out—expect some flux over the next few days. Fewer than 0.7% of queries noticeably affected: http://t.co/QqlpqTmk
Some thought there had been a Panda update last week, but it turned out that webmasters were apparently seeing the effects of a different update Google's Matt Cutts later tweeted about. Google was, however, about due to launch a Panda refresh, so here we are.
We should be seeing plenty of webmaster feedback about this throughout the week. Have you noticed any changes to your Google referrals yet? Let us know.