There are several utilities — all with different procedures, limitations, and target operating systems — for getting a Python package and all of its dependencies and turning them into a single binary program that is easy to ship to customers:

• http://wiki.python.org/moin/Freeze
• http://www.pyinstaller.org/
• http://www.py2exe.org/
• http://svn.pythonmac.org/py2app/py2app/trunk/doc/index.html

My situation goes one step further: third-party developers will be wanting to write plug-ins, extensions, or add-ons for my application. It is, of course, a daunting question how users on platforms like Windows would most easily install plugins or addons in such a way that my app can easily discover that they have been installed. But beyond that basic question is another: how can a third-party developer bundle their extension with whatever libraries the extension itself needs (which might be binary modules, like lxml) in such a way that the plugin's dependencies become available for import at the same time that the plugin becomes available.

How can this be approached? Will my application need its own plug-in area on disk and its own plug-in registry to make this tractable? Or are there general mechanisms, that I could avoid writing myself, that would allow an app that is distributed as a single executable to look around and find plugins that are also installed as single files?