MarketingShift search blogger Jason Dowdell conducted his own experiment into the originality of all the various links that come back from the major search engines - initially an attempt to test new search entrant Become. After eliminating results found in several of the major search engines, he found that each of the majors had relatively few unique offerings. In fact, newbie Become.com did best in the several tests he conducted (on shopping related terms).
Become beat Google by at least one and a half times the quantity of URLs unique to its search results.
Dowdell speculates that Yahoo and MSN, trying to catch up to Google, have been deliberately nibbling away at the unique URLs they find in Google's results, slowly improving their own.