One of Facebook’s most excellent “secret” features is that it is actually doing OpenID while everyone else is merely talking about it
I have joined every Facebook App possible (check for yourself) and I have never needed to register for any external 3rd party app. Facebook is acting as my proxy and is signing up on these external application on my behalf; additionally, Facebook integrates the external application and takes care of all authentication based on my having logged into Facebook just once.
In other words, Facebook is actually becoming a highly-trusted change-agent for OpenID trust nets while all the ubergeeks are mentally-masturbating about it.
Filed under: Facebook, OpenID, Social Utilities










Using http://identitu.de you can extend this further by having an OpenID proxy over your Facebook account
So you can use your Facebook account at 3rd party sites supporting OpenID but not running on the Facebook platform.