However, Facebook Connect seem to be leading the way with regards to the promise of taking your network of friends and connections around the web with you. There are, of-course, concerns about whether we should trust a commercial enterprises with our precious identity. Nevertheless, I'll highlight Facebook Connect as the principle is important.
From the Wikipedia page on Facebook Features:
Facebook Connect is a single sign-on service that competes with OpenID. The service enables Facebook users to login to affiliated sites using their Facebook account and share information from such sites with their Facebook friends.The price of Personalization is Privacy. I don't mind sharing my information if it's going to get me more relevant information and personalized service, but I would expect to be able to control what different people (and sites) can see on my profile. Another concern with single-sign on is the danger of someone getting hold of your one password that opens the doors to your life online. I guess these are the risks we all have to live with. I'd like to get Dominic White's perspective on this.