This document, Open Trust Frameworks for Open Government, is about a year old, but still provides an excellent overview of how OpenID and Information Card technology are being applied to provide citizen access to government websites:

Open government requires a way for citizens to easily and safely engage with government websites. Open identity technologies—specifically OpenID and Information Cards—fit this bill. They make it easier and safer for citizens to register, login, and when necessary share personally identifiable information across different websites and services. To bring open identity technologies and open government together, the OpenID Foundation and the Information Card Foundation are working with the U.S. General Services Administration to create open trust frameworks for their respective communities.