OpenID is of use to educational applications because it allows for them to interact with the many Web 2.0 applications in wide use today. Many educational institutions adopted a federated approach - such as Shibboleth - which leaves identity management in the hands of the institutions (and which, pointedly, does not operate outside the federation, that is, not outside the institutions in question). I argued at the time that the federated approach was the wrong one, and the reason was that a distributed system such as OpenID would enable much greater interoperability. We are seeing the proof of that argument today. See also Simon Willison on the impact of OpenID.