Recently I have seen people giving advice how to use CPAN to install the perl modules that Koha depends on. Now for non .deb based systems (Redhat, Centos, etc) this advice is ok. But if you are use a Debian based distro, like Debian, Ubuntu, Mint, etc please use the packages.
If it is not in your distro proper, you can get the packages from debian.koha-community.org. As new dependencies are added, we package them and submit them to Debian, so they end up in the next release, but you can always get them from debian.koha-community.org until then.
A really easy way to get them is of course to just install the koha-common package from there. You can read good instructions at http://wiki.koha-community.org/wiki/Debian or there is the koha-perldeps package which only pulls in the dependencies.
Why not use CPAN? Because then it is up to you to make sure you keep all your installed modules up to date, and with the latest security patches. Or you could let the package maintainers worry about that instead.
If you do bump into a module that isn’t packaged, let us know and we will fix that right away.