There are some rumblings that Google may have made a significant update to its algrorithm this week, sometime in the vicinity of August 28. Search Engine Roundtable points to a WebmasterWorld forum thread where some webmasters are commenting on substantial changes in their traffic - some positive, some negative.
Here are a couple sample comments from the forum:
"20% google traffic improvement as of yesterday... Only about 500% left to go to get back to normal... But like the direction!"
"I noticed a massive drop in long tail yesterday. Our site only went live in June, and there have been no indications of Panda/Penguin."
One reader commented on the SER post, "I'm seeing a very obvious increase in traffic for several large clients, two of which their traffic has increased by about 25% or so - Obviously something is going on, but at least (for once) it doesn't seem to have affected me negatively!"
Dr. Peter Meyers, who recently shared that interesting data bout Google SERPs with less than ten organic results, at SEOmoz, also commented on the article, indicating that he's seen "no sign of anything major," based on MozCast numbers.
There is question as to whether or not Google has tweaked the Penguin update. Another person commenting on that post noted that the lack of more comments doesn't seem "jarring and jolting". This is in reference to what Google's Matt Cutts recently (reportedly) said at SES about what to expect from upcoming updates.
Google updates its algorithms over 500 times a year. Some have far greater impact than others. This could be one of those not so major ones.
We've reached out to Google for comment, and will update if we receive one.