I've been doing research in IBM's internal project on Identity 2.0, at that time supported by Tivoli and the IBM's CIO. We've established an abstraction for Identity 2.0 protocols with potential implementations for anonymous credential systems and other user-centric identity management protocols. At that time, I've been a contributor to the open-source project Higgins, contributing to the Identity Mixer Secure Token Service (STS) plug-in and Identity Selector Service.
Abhilasha Bhargav-Spantzel, Jan Camenisch, Thomas Groß and Dieter Sommer. User centricity: A taxonomy and open issues. In Journal of Computer Security 15(5): pages 493-527, IOS Press, 2007