From Dogpile’s release:
Dogpile announced the integration of search results from MSN Search to their industry-leading metasearch technology that combines the best results from the Web’s top search engines. With this announcement, Dogpile will be the exclusive home to all four of the Web’s leading search engines—MSN Search, Google, Yahoo and Ask Jeeves.
While most people believe search results across all four engines are the same, the reality is the vast majority of the results from each engine are different and do not overlap. This fact was validated by a new study conducted jointly at the University of Pittsburgh and the Pennsylvania State University… (which found that) only 1.1% of page one results were the same on all four engines.