The debian <--> CPAN interface is easily managed, and there are more that a thousand CPAN modules in debian. (See the debian-perl web site: http://pkg-perl.alioth.debian.org/)

The great thing about debian packages is that they not only manage all your perl dependencies for you, but they also manage operating system dependencies too. Gems can't do that.

The Perl Foundation actually holds up debian's packaging work of CPAN modules as the model for other distributions. (See http://www.perlfoundation.org/perl5/index.cgi?hints_for_dist...)