VirtualEnv/PIP (virtualenv) is a rather lameish Python script written by Ian Bicking et al for creating naive and quite restricted virtual sandboxes for Python based development.
Highly popularized and over-rated script. Not very recommended except for its requirement to duplicate Python packages and to break standard Python functionality for very little gains. It also may be a lame trap for unexperimented Python developers wanting to setup boring websites without worrying about licensing terms, as in PHP.
As for Django development itself, the logic of keeping Django source code hard to access and manage, is a pain, not an advantage for the competent programmer seeking ProgrammingFreedom.
The CPAN website: http://www.cpan.org/