Aldo has an interview with Drummond Reed, Johannes Ernst, and Chris Messina talking about the importance of usability design and user experience to OpenID.
Like Kim, they refer to the importance of ceremony for users around identity transactions. Pam touches on the same.
Chris refers to the possible advantage of, at least initially perhaps, allowing for experimentation. Let different communities try different ceremonies and user interface paradigms and learn from the collective experiences. Fundamentally, recognize that we have much to learn here and we probably shouldn't think we can get it right the first time. This belief (admittedly as well as a recognition that user interface design was a potential differentiator for vendor's offerings) is the primary reason that the Liberty Alliance has never attempted to tackle this aspect of identity.
Separately, from the chat, you might get the impression that mobile clients present no special challenges or opportunities for user ceremony. It's hard enough for me to enter my email address on a phone but I'll take the 5 minutes to type in URL? How many users know how to find the '/'?
Update: I wrote the above before I got to the point of the interview where Johannes does briefly mention devices.
Aside from that, all other ceremonies I attend always end up with me wearing a suit. That's going to significantly slow down my log-in.