Google just announced Social Search. The services helps you “to find publicly available content from your social circle”. Google extracts information on your social circle from three sources: Google Reader subscriptions, Google Profiles, and Google chat (GMail). They use the term “surfacing” connections to describe not only adding your friends, but one additional degree: your friend’s friends.
This move by Google is a direct assault on Facebook. Facebook has emphasized social connections over content. Google has, to date, primarily emphasized information sorting, filtering, and ranking. Facebook’s model of emphasizing social rather than information connections is a problem for Google. What is unique in Social Search is the focus on aggregation rather than place-based interaction. In theory, Google emphasizes pulling together various pieces of online interactions through aggregation, whereas Facebook emphasizes housing interactions in their environment.
An introductory video is available here.