Last year Google released the Social Search experiment to make search more personal with relevant web content from your friends and online contacts, and social search is available to all in Beta at google.com today.
Social search at Google has proliferated since it was launched, for example, there is social elements in Google Images. Now when you're doing a search on Images, you may start seeing pictures from people in your social circle. These are pictures that your friends and other contacts have published publicly to the web on photo-sharing sites like Picasa Web Albums and Flickr. Just like the other social results, social image results appear under a special heading called "Results from your social circle." Here's what it looks like: 
You can check out your social circle directly by visiting this link. (Note that it may take some time for the connections and content to update.)
Google believes there's tremendous potential for social information to improve search, and are just beginning to scratch the surface.
If you want to get the most out of Social Search right away, get started by creating a Google profile, where you can add links to your other public online social services.
The new features are rolling out now on google.com in English for all signed-in users, and you should start seeing them in the next few days.