From CommonJS Spec Wiki
Packaging, installation and deployment
One of the most important parts of this project is to provide a repository for code releases and an easy way to install that code for development and production uses. Possibly the most successful example of this is Perl's CPAN. Python has its Cheeseshop (also called the Python Package Index) and Ruby has gems.
It is important to work alongside the Linux distro packaging mechanism, but for Windows, Mac users and people who want to run something that is not yet in their distro, having a language specific installation process is critical.