Fireworks-Package-Server is a project mainly written in Python, it's free.
A CommonJS compliant package registry.
This is a package server created by the Fireworks Project that is to be fully compliant with the emerging CommonJS specification. See:
(http://wiki.commonjs.org/wiki/Packages/1.0) (http://wiki.commonjs.org/wiki/Packages/Registry)
Django was selected at least as an initial starting point for both the ORM and the ease of initializing an admin interface. Discussion has not yet started on a final platform, though GAE has been mentioned.
You can easily play with the system by taking the following steps:
mkdir data
../manage.py syncdb
../manage.py runserver
.