When you sign into Facebook or Flickr whilst using Flock you will have access to a list of your friends via the People Bar.
Flock does this by calling the Facebook / Flicr API’s
Here is an example request as seen in a wireshark dump:
GET /restserver.php?query=SELECT uid,name,pic_square,status,profile_update_time
FROM user WHERE uid IN (SELECT uid2 FROM friend WHERE uid1 = 123456789)&
api_key=123456&session_key=12345&call_id=12345&method=facebook.fql.query&
format=JSON&v=1.0&sig=12345
HTTP/1.1
Host: api.facebook.com
(flock facebook code: http://svn-mirror.flock.com/trac/flock/browser/trunk/mozilla/flock/base/services/ )
Flickr is accessed a similar way, via their rest interface – eg:
GET /services/rest/?method=blah.blah
Host: www.flickr.com