Dogpile, a meta search engine owned by Infospace (along with WebFetch, Web Crawler, Meta crawler, Nation, Infospace, DoGreatGood search engines) provided this research in 2007, but it is still pretty interesting (and I just found this cool graphic representation that was updated on the Dogpile website, so I thought it was time to share…-)

Link to research document – Search Overlap Study

Search engine link – Dogpile

Also, just a quick side note. Infospace recently got its flagship domain back from another company which it sold it to 2 years ago (a long story, so read about it here – InfoSpace looks to claw its way back into the search business). What I found interesting is that it beat both Google and Yahoo to integrating Twitter into it’s search results without much fanfare – just an FYI.

Check it out here – Infospace Search Engine