I put together a quick perl script for comparing installed CPAN modules between two hosts. Find it here.
Quite easy to use:
Usage: ./CompareHostCpanModules.pl login@host1 login@host2
The script ssh's into both hosts (so it's easier if you have your ssh-keys setup) and grabs a list of installed CPAN modules and versions, then outputs the differences - it returns two lists - one of modules installed but having different versions, and another list of modules missing from the second host.