In short, Matt said he did not see “large differences in rankings between these datacenters,” but he would like more feedback from the webmaster community. To submit feedback, he asked for webmasters to use this form and place the word “dewey” in the “Additional details” text area on that form. By doing so, they will review specific cases to this Google algorithm change and use that feedback to help improve the quality of the search results.
So since Matt asked us to use the word “dewey,” why not code name this Google update the “Dewey” update? It has been a while since we named a Google update, and this is the first major update we have seen in a while that has really been widely noticed.
More details can be found at the Search Engine Roundtable.