Buildout is a "system for managing development buildouts".
While often identified as a Zope project, and indeed licensed under the ZPL by Zope creator Jim Fulton, buildout is useful for configurations beyond Zope, and even, in rare cases, a few that have nothing to do with Python. The home page includes extensive documentation, examples, and more.
At one level, buildout (still referred to as "zc.buildout" on occasion) manages eggs.
[explain relation to easy_install and eggs; workingenv.py and virtualenv.py; explain usage]
Other treatments of buildout include:
Martin Aspelli's book on Plone 3, which includes a good reference on buildout;
the Zope 3 Wiki includes a useful page on the subject;
Jim wrote a tutorial;
A proposal is being floated to create a more professional site for buildout. At a first step, let's collect notes on what such a site would contain.