It appears that the pam module pam_pwdb.so is not part of fc5 ( it is present in fc4).
This broke my pop3 server gnu-pop3d.
I found two workarounds
1) copy pam_pwdb.so from fc4 ( and the config file in /etc).
2) for this particular program I was able to recompile to not use pam.
Was this an oversight by the packaging crew or is there a workaround for
programs that use pam_pwdb.co ?