Myself and my colleague Tammy DiPrima have implemented WebID authentication and provisioning for VIVO (http://www.vivoweb.org).  WebID is a way to uniquely identify people and agents with a URI and provide a central identity and authentication system based on digital certificates.  WebID is being developed by the W3C WebID Community group. VIVO is a faculty/researcher profile system developed by Cornell, University of Florida, Indiana University, Washington University in St.