This is a great presentation, the clearest dscription of Shibboleth - a system that shares user authentication between participating universities - that I've seen. Especially useful is Slide 7 (be sure to view this in presentation mode) which shows step by step how the parts of Shibboleth interact. There's a lot to like about Shibboleth, but what I don't like is that it is more or less a closed network and that a user's identity is handled by, and distributed by, the university system. What we need is a home Shibboleth, a desktop application readers can run themselves without the need for a (very expensive) university enrollment. Via EDUCAUSE.