Barry Schwartz wrote on Search Engine Roundtable that Google may be prepping for a large update to their search algorithm.

From the article:

I mentioned there was some chatter about a Google update on May 2nd but now we are seeing even more chatter and signs of flux in the Google search results on May 7th.

These signs of shifts in rankings, spikes in crawl rates, often, but not always, are early warning signs of a major Google update happening in the near future.

Here are flux/volatility charts from MozCast, SERPS.com, SearchMetrics and Algoroo:

Read the full article here and check out the various chart patterns Schwartz identified.

There is a discussion on WebmasterWorld

The comment section on the post had a mixed reaction to the post, as some said they have seen some of the changes, while others did not think it was much of anything.