Yahoo!, if you did not know, invests heavily in social search. From MyWeb, to desktop search to Flickr and Yahoo! Video - social, tagging and all that fun Web 2.0 stuff is something Yahoo! takes seriously.
Yahoo! hired "Dr. Raghu Ramakrishnan, 45, as vice president and Yahoo research fellow in charge of defining the strategy behind Yahoo's "social search" system, based on his expertise in databases, data mining and privacy-preserving technologies."
Hopefully this will make things more interesting over at Yahoo!
Forum discussion at WebmasterWorld.