Influencing your web presence - Google Social Search

"your social circle", is based on Google Social Search, which relies on the content of your Google Profile (e.g. erich13)

Watch a video overview of Social Search

"Your social circle is essentially a group of connections including these contacts:

• People in your Gmail (or Google Talk) chat list
• People in your Friends, Family, and Coworkers groups in your Google contacts
• People you're publicly connected to through social sites, such as Twitter and FriendFeed, that appear on your Google profile or in your public Google Buzz stream.
• People you’re following in Google Reader and Google Buzz
• People who are connections of those in your immediate, public social circle. This means that if you have a friend on Twitter, and he follows five people, those additional five people may also be included in your social circle."