Not to say that SESAME was ever widely prevalent but it did have valid use and was extended/modified with the advent of RFC 1510. For instance, SESAME was part of secure CORBA implementation. I can't comment on a large ORB system that I know was in place even within the last 7 years but it did exist - presumably at the later stages only superficially... For non-SESAME related issues, the system to which I refer was purported to be replaced.
I would doubt that any large scale systems use SESAME. I wouldn't bet my life on it though because it I've know companies that just retired historic SPARCs. (Europe also surprised me before by running Amigas well beyond the death of Commodore. Awesomeness.)
Anyhow, my theory (not fact) is that SESAME was extended to use the Kerberos 5 data structures as a way to ease transition by keeping the system's APIs consistent while replacing the backend. Ultimately, newer systems and code would have no legacy ties thereby slowly putting in nails into the SESAME coffin.
So my commentary, obscure knowledge, and personal theorizing is just that. In general, I think you're more likely to win two lotteries back to back than to encounter a SESAME implementation. ;-)
So Schroeder's reply is solid; I'm just adding unnecessary color to it for those that are interested.
After typing this, I Googled and found published current references in International Journal of Computer Applications (0975 – 8887) Volume 89 – No.4, March 2014: Improving the Security of SSO in Distributed Computer Network using Digital Certificate and one Time Password (OTP), Patel and Patel. This paper's references seem to have 2005 link to what my be an actual implementation.