Update: What do you know? They just formally announced it (and it's just a data refresh, not an actual update):
Panda data refresh rolling out. ~1.1% of English queries noticeably affected. More context: http://t.co/QqlpqTmk
Google has without question been more transparent about algorithm updates over the past year or so. However, the search giant has shown a great deal of inconsistency around this transparency. Take the Panda update, for example. Sometimes, the company will announce that there has been a new update or data refresh. At the end of September / beginning of October, we saw Google announce a handful of updates, and eventually announce a Panda update about a week after it happened.
According to Danny Sullivan at Search Engine Land, Google confirmed that a Panda update happened yesterday, though this was not announced. Sullivan reports:
"Google said that worldwide, the update will impact about 0.4% of queries that a regular user might notice. For those searching in the United States in English, the percentage is higher. 1.1%, Google says."
Also yesterday, Demand Media (which some might say is the poster child for Panda update affected sites) released its quarterly earnings report, posting record profit and revenue.
With regards to Google algorithm changes and transparency, we're still waiting to see the company's list of "search quality highlights" for the month of October, though they might wait and do October and November together.
Image: Panda Express