Shibboleth is a widely deployed federated identity solution that originated with Internet2. It is based on SAML 2.0.
InCommon is the US higher education federation. It's members are educational institutions and the corporations they sponsor. InCommon is a member of eduGAIN, a federation of 48+ national federations like InCommon.
At this point in time, Shibboleth at NDSU is only for use with InCommon service providers. InCommon is the preferred mechanism for authenticating to third parites, with CAS as the backup. The preferred mechanism for entities at NDSU is still CAS.