Google is now showing social search related results in the Sitelinks section of the search results. The social sitelink includes your friend’s name, profile photo, and it links to your friend’s content on a particular website.
For example, if I search for [twitter] on Google, I see Robert Scoble (scobleizer), Steve Rubel (steverubel), Israeli Consulate (israelconsulate) and Matt Cutts (mattcutts) in my Sitelinks. Here is a picture:
Google explained these social sitelinks come from their Google Social Search technology.