What a wild several days with Google updates - we had fluctuations on July 11, 12 and 16th and then some massive chatter and Google search result fluctuations on July 18th or so. Google would not confirm or deny these updates, so it was named by the community the Google Maverick Update.
It seems as of the past few days or so things have significantly calmed down. Here are the charts showing the past 30 days or so of changes from the tools that track it.
I won't share all the tools but you know where they are.
It seems things have calmed down - but who knows, it was one insane week or so and no word from Google on what happened. So much for all that transparency.
Forum discussion at WebmasterWorld and Black Hat World.