A couple of months ago Google launched its Social Search feature in an
opt-in beta. This new search feature was intended to enrich SERPs with
results from your social media contacts.
Surviving a mixed reception for this new search feature, Google seems to see
the value and is intent on developing it further. Yesterday they announced further improvements to Social Search rolling out to all
English-language users that are signed in on google.com.
One such improvement is the implementation of Social Search in Google's Image Search. Image SERPs will now also be enriched with Social Search results from your contacts, for example from your friends' Flickr and Picasa accounts.
Two additional new features are 'My social circle' and 'My social content'.
The social circle feature allows you to see exactly which users Google has determined are part of your social circle and thus influence your Social Search results. Google derives your social circle from your Google chat contacts, your Twitter and Friendfeed contacts, and 'secondary connections that are publicly associated with your direct connections', i.e. friends of your friends.
The social content feature shows what websites Google uses to enrich the Social Search results of your contacts. So if for example you have a blog, a Flickr account and a Delicious account, Google will use these for Social Search results throughout your social circle. You can influence what sites Google uses for Social Search by linking to them on your Google profile.
Google appears to be pretty good at finding your accounts on various websites and using the content you post there for its Social Search. There doesn't seem to be an opt-out function that allows you to remove sites/accounts from Social Search. If it's public, we can use it, seems to be Google's approach.