I myself use Debian stable and in more than 4 years I needed only twice a module not deb-packaged.
... mostly shows that you don't run foreign code very often. (Or under-use CPAN).
Want to run a jifty application? Need to build and install about 15 more Debian packages. Tired of HTML::Template and want to try HTML::Template::Compiled? Build a new .deb. Heck, not even Text::Table is in Debian.
Many recently updated modules also depend on minimum versions of others that are too old in Debian.
During using Debian Etch I assembled a collection of nearly 100 perl modules packed up as Debian modules. And I fear the upgrade to Lenny, because it introduces perl-5.10.0, breaking many of these modules ("breaking" here means that I have to recompile them).
So what I'd really want to see is a CPAN mirror that automatically builds debian packages out of new modules, and places them into a local Debian mirror. Any takers? ;-)