> unpriviledged mode, all those variables could be overwritten with the 
> local user:

many packages already today use such variables.
The first issue is with packages that have users hard-coded, such as
comms/minicom. The only solution I guess is to modify them to use variables
such as UUCP_USER? Does something like that already exist for other
packages?
comms/kermit uses KERMIT_SUID_UUCP as another mechanism.

-- 
Georg Schwarz    http://home.pages.de/~schwarz/
 georg.schwarz@freenet.de  +49 178 8545053