The New York Times has an article by James Fallows who spent a day at Yahoo recently:
[The chief technology officer, Farzad Nazem] and everyone else really wanted to discuss what lay beyond these keyword searches of the entire Web. “You can look at the evolution of search as a play in three acts,” said Jeff Weiner, the senior vice president for search and marketing. “The first is the ‘public’ Web, where if different people type the same query they’ll all get the same results.” The second, he said, was purely personal search – finding a file or photo, usually on your own machine.
“The third is the one that we are very interested in,” Mr. Weiner said. This is “social” or “community” searching, in which each attempt to find the right restaurant listing, medical advice site, vacation tip or other bit of information takes advantage of other people’s successes and failures in locating the same information.
The idea that human judgment can improve a search engine’s automatic findings is hardly new. From the dawn of the Web’s history – that is, over the last 15 years – companies have invented tools to help users assess the quality and relevance of information, often by relying on others’ opinions. Examples include Amazon’s user reviews, eBay’s feedback ratings and “trusted networks” created on many sites.