I am seeing significant signs of a real Google update both in terms of summer/weekend forum chatter at WebmasterWorld, via the automated tracking tools and via emails sent to me with screen shots.
The update seems to have around August 9th or 8th and has continued through the weekend.
Here are some quotes from the WebmasterWorld thread:
I concur with the above observations. Seeing a huge drop in traffic volume and conversions, but spidering is going ballistic!
I join samwest, with big drops, hours with -95% traffic with folloowed spurts of traffic. Overalltraffic is at about 60%. Bounce is near 100%. And yes we changed a little bit the navigation but this is about 8 weeks ago. I know of two others seeing the same. It feels like a new panda.
Here are screen shots from the various automated tools at MozCast, SERPS.com, SERP Metrics and Algoroo:
Alex, a reader, also emailed me screen shots, limiting his analytics to show Google Organic referrals only. He showed how his site was nailed back with the January 9th update and recovered on August 8th:
And his webmaster tools:
Alex also feels this is a major Panda refresh.
I will try to get Google to comment on the update and will keep you posted.
The interesting part, the forums are not lighting up as much as I would expect. But again, it is a weekend and summer weekend update.
Forum discussion at WebmasterWorld.
Update: Google won't comment on this update.