To enable mod_perl with Apache2 on Debian & Ubuntu for all directories served up by Apache2, including user directories such as ~/public_html, add the following lines to /etc/apache2/sites-available/default

# enable mod_perl
    <Files ~ ".(pl|cgi)$">
           SetHandler perl-script
           PerlResponseHandler ModPerl::Registry
           Options +ExecCGI
           PerlSendHeader On
    </Files>

In a real production environment you probably don’t want to enable this for all directories that Apache2 serves up, but only from those directories you expect to run perl in.

Thanks to this thread on the Ubuntu Forums for the info.

Titled updated as per Ozkar’s suggestion.