Cool! I'm looking at building a server to be an identity provider and wiring it up to a really simple smtp server, imap client (for pulling from gmail) and imap server to make a really stupid simple email client that provides identity services with a variety of options for security. Multifactor auth with a variety of choices in factors : SMS, phone call, OTP, time based codes, PKI, etc.

I think the federated nature and options in security along with the eventual UserAgent integration has the potential to give users and integrators a really fast, easy UX. More than OpenID ever did, certainly.