We rarely cover Google updates these days, since it appears Google is in a constant flux. But I have noticed a dozen or so threads at DigitalPoint Forums and an updated WebmasterWorld, plus a few threads at Google Webmasters Help discussions on the topic of either a back link update, PageRank update or major drops or increases in rankings for specific categories.
Now, this does not mean there is a massive update going on. In fact, I would classify this as a minor update possibly only impacting specific sites that may have triggered a new penalty or just random fluctuations in Google that some webmasters took notice to.
In any event, if you noticed a major change for your site in Google, you are not alone. It is not as 'huge' as some of the past updates, but it seems like many are discussing this specific, possible update.