Want to know who is in your social circle? Head straight to your Google dashboard at http://www.google.com/dashboard and scroll down to Social Circle. This not only tells you which of your social networks Google is using but also lists who.
Any social networks that you have mentioned in, for example, your Blogger profile or your general Google profile such as Twitter will be included as will contacts in Google Reader, Google Buzz, Google Contacts and Picasa. In addition to your direct connections Google also searches the content of secondary connections that are publicly associated with your direct connections. The A-Z reveals all!
I’d missed this, but it’s quite interesting – including how many people *haven’t* set up a Google profile. My issue is this not working for my main Google Apps For Your Domain accounts.