Social Circle
The concept is simple: If Google shows you what search results people in your social circle are talking about, those links are likely to be more relevant to you than others.

That's why, in February, Google brought its Social Circle product to the forefront of its search results. Comments that people in your social circle have made now appear below individual search results.

In practice, however, Social Circle has kicked up some controversy.

Google compiles a list of your social connections not just through its own products like Gmail, Google Reader and Google Buzz, but also through third-party applications that make connections publicly available, such as Twitter and FriendFeed.

Facebook attempted an ill-fated PR campaign to show that Social Circle is a "sweeping violation of user privacy." The social network claimed that people are largely unaware that their social graph is being mapped by Google.

Last updated May 23 2011: 5:38 AM ET
Join the Conversation

Euros, private investments, telecoms as utility companies, and of course, Fukushima. 2011 has brought sweeping change to the world of green More

The media has called every breaking news event since Twitter's launch the service's coming of age. Here's the proof that Twitter is all grown up. More