Note that this feature is (for now, at least) designed to add weight to content _created_ by your social circle.  It does not, as I first thought, modify your search results based on friends' preferences.<p>From Google's FAQ:
"Google Social Search is a feature designed to help you discover relevant publicly-accessible content from your social circle, a set of online friends and contacts. The idea is that content from your friends and social contacts is often more relevant to you than content from strangers. For example, a movie review from an expert is useful, but a movie review from your best friend can be even better."<p>More info here:
<a href="http://www.google.com/support/websearch/bin/answer.py?hl=en&#38;answer=165228" rel="nofollow">http://www.google.com/support/websearch/bin/answer.py?hl=en&...</a>