When Google updates, SEOs around the world hold their breath. For websites that rely heavily on their Google SERPs for traffic, an algorithm change can sometimes mean the difference between profitability and the poorhouse.

Google’s newest update, named Caffeine, is by all appearances more than just a regular update. Google describes it as a “next-generation architecture for Google’s web search“.

According to a post yesterday on Google’s Webmaster Central blog, Caffeine represents “the first step in a process that will let us push the envelope on size, indexing speed, accuracy, comprehensiveness and other dimensions“.

Fortunately for SEOs and webmasters, Google is breaking with tradition and is soliciting feedback from the webmaster community by opening up a preview of the Caffeine update, which can be accessed at http://www2.sandbox.google.com/.

As you can see, there aren’t many noticeable changes to the UI. In fact, you probably won’t notice much difference at all. According to Google’s Matt Cutts, “this update is primarily under the hood” and has involved “rewriting the foundation of some of our infrastructure“.

And yes, that means that there will be some changes in site rankings. From my limited initial tests, the impact on rankings seems subtle — most of the time.

One exception appears to be social web results. For instance, certain high-profile Facebook Pages appear to be receiving a major boost in the rankings with Caffeine. One commenter on the Google Webmaster Central blog also noted “I’ve noticed more Twitter pages in the results with this version of Google“.

When it comes to the latter, Starbucks serves as a good example: through a US proxy, Starbucks’ Twitter account appears fifth on the first page in the current Google SERPs; it appears third in the Caffeine preview. While this is a minor shift, I’ve seen significant shifts with several Facebook Pages, leading me to believe that Google is not only placing increasing emphasis on pages in the social web but is getting better at sorting out which social web results are ‘the real deal‘ and which are spam.

If this proves to be the case across the board, it will be more reason for some to consider the social media SEO link.

Are you noticing any important or interesting changes? Be sure leave comments with your observations. I’d love to hear them!

Photo credit: carrinated via Flickr.