Introducing Google Social Search:

Your friends and contacts are a key part of your life online. Most people on the web today make social connections and publish web content in many different ways, including blogs, status updates and tweets. This translates to a public social web of content that has special relevance to each person. Unfortunately, that information isn't always very easy to find in one simple place. That's why today we're rolling out a new experiment on Google Labs called Google Social Search that helps you find more relevant public content from your broader social circle. It should be available for everyone to try by the end of the day, so be sure to check back.

http://googleblog.blogspot.com/2009/10/introducing-google-social-search-i.html

Alberto