I knew Gene Kan, barely. He and Yaroslav are friends with my friends, and are occassional visitors. Gene was in my office a few weeks before his death, installing an email server in a machine room. Why would a man expecting death build an email server to last a decade? I do not know.
Role-based access control
There is a SIG in the ACM for role-based access control (RBAC). They meet every year for a symposium. A lot of papers are presented. I cannot see anything in all the RBAC literature which is more functional than putting users into groups the old-fashioned Unix way. My machines using regular Unix security have many role accounts: httpd, nntpd, ftpd, lpd, uucp, daemon, nobody, and so forth.
The main problem with the Unix authorization model is the lack of delegation of authority, but this is a separate issue from RBAC.