I used to be Freeserve+Wanadoo's digital identity futures guy - providing technology intel on Hailstorm, Liberty Alliance, Sxip and LID; eventually some of our work contributed to the adoption of OpenID across Orange.
Throughout this work, no initiative ever seemed to begin with a simple exploration, storyboarding or visualisation of a user's journey or experience of a federated or shared identity. Consequently, the underlying technologies worked well, but failed to anticipate the motivations of real users.
Lately, I've been feeling the same anxieties on the development of standards around Open Data principles and Data Portability. Though individuals such as Marc Hedlund, with Wesabe's implementation of a Data Bill of Rights, have come at it from a user-centric perspective. It's about time some interaction designers got out ahead of the technology, schemas, standards and formats to understand how we'll all experience data interoperability, portability and sharing in a practical sense.
There are some clues in the design of applications like Flickrfs and the notion of a familiar filing system metaphor, but perhaps they aren't entirely appropriate...personally I feel the experience should be as simple as synchronising a pair of connected devices...hence my tongue in cheek visualisation above ;)
Sure synchronising, images, metadata, music, playlist, messages, social graphs and other media between web applications belies a great deal of technological complexity, but shouldn't the role of great design be to encapsulate complexity within simplicity?