Matt Cutts posted a video on YouTube that confirms Google's recent Mayday update and its effect on search results. It looks like Mayday addresses a change in the SERPs that affects mostly long tail searches.
He doesn't really go into much detail, but it could explain the recent drop in traffic that many sites are seeing. Although Google calls the change a winner, it doesn't appear that many people at Webmaster World would agree. Google MAYDAY Update - SERP Changes May 2010
2 June, 2010, 16:10 PM
Many webmasters believe that the changes to the long tail traffic are due to phrasification and phrase based indexing.
2 June, 2010, 18:24 PM
That would explain the change in long-tail searches. It looked to me like an exact match phrase was working better than a keyword phrase. In other words, in the past "DUI lawyer Phoenix" returned the same results as "DUI lawyer in Phoenix" because the stop word "in" was ignored. Today a search like that returns slightly different results.
2 June, 2010, 22:18 PM
Google AdWords already uses phrase matching to display ads against keywords with the exact match and broad match options. The patent for Phrasification was filed in March 30, 2007, but just recently granted on April 6, 2010. My guess is that the new caffeine infrastructure gived Google the ability to use Phrasification in new ways outside of adwords. Rad more about Google Phrasification Patent here -- http://patft.uspto.gov/netacgi/nph-P...S=PN/7,693,813
The long tail keyword volume increased substainly after the supplemental index was better incorporated into the main index. Thus, Phrasification will lower the long tail volume. So the question is why use phrasification as opposed to the long tail results?
2 June, 2010, 23:20 PM
The webmaster world post is interesting in the theory that they were using two sets of data (or are doing so actively)...would explain some variations that I've seen over the last 6 weeks...Thanks for sharing!