>It means a slight change to your existing AFS code, yes.

You're saying that it's _slight_.  I strongly disagree.  (AFS was just
one example - another is Kerberos, that wants to set an environment
variable.  Yes, I could pass the environment variable to set via any
one of a number of message-passing systems, but if I have to start
teaching the upper layer about each authentication system I want to
use, then the battle has already been lost, IMHO).

--Ken