Karls-Mac-mini:~ karl$ cpanm -V 
cpanm (App::cpanminus) version 1.5019

Karls-Mac-mini:~ karl$ perlbrew list
* perl-5.16.2

Karls-Mac-mini:~ karl$ which perl
/Users/Karl/perl5/perlbrew/perls/perl-5.16.2/bin/perl

Karls-Mac-mini:~ karl$ cpanm MLDBM
MLDBM is up to date. (2.04)