In the past 20 hours or so, I have seen a huge uptick in the number of complaints in the Google Webmaster Help forums with people complaining that their sites no longer rank in Google.

Update: This is not the “over optimization” penalty as we thought. Matt Cutts posted on Google+ it is related to a “classifier for parked domains” which went haywire. Google fixed the issue, Matt said:

So I guess we are still on a holding pattern for the over optimization penalty.

Here is the rest of the post as it was…

I captured 11 different complaint threads before stopping, I suspect there are about 25 or more complaint threads and many many more webmasters suffering from a possible Google update. Here are some of those 11 threads; #1, #2, #3, #4, #5, #6, #7, #8, #9, #10, #11 and many more.

The ongoing WebmasterWorld thread has taken notice of this as well. One said:

Google has not officially announced something yet, but this can very well likely be the overly SEO penalty Matt Cutts pre-announced. Keep in mind, we had a Panda update a few weeks ago, Panda 3.4.

Did you notice major changes in the search results?

Forum discussion at Google Webmaster Help.