Perlbrew is a program to automate the building and installation of perl in the users HOME. At the moment, it installs everything to ~/perl5/perlbrew, and requires you to tweak your PATH by including a bashrc/cshrc file it provides, in your shell configuration file. You then can benefit from not having to run 'sudo' commands to install cpan modules because those are installed inside your HOME too. It's a completely separate perl environment.