You can use pacpan in a script to get the latest versions (and to generate PKGBUILDs with extensive provides arrays (many CPAN modules use the same sources and thus create the same package even though they use different names)). http://xyne.archlinux.ca/info/pacpan
You can also use makerepo with pacpan to automatically build newer packages when new module versions are released. http://xyne.archlinux.ca/info/makerepo
Xyne
pacpan is surely an excellent option. I have myself developed a similar tool (perl-cpanplus-pacman on AUR) but I have not touched it much since last year, and I presume pacpan is more usable now. I have also a small perl script to check for out-of-date version of CPAN stuff. See http://ankabut.net/archlinux/checkcpanversions.pl (Change the variable $cpandir to suit your situation). Best, F