As the #1 google result for “python plugin”, the linked to blog post is extremely valuable for jump starting research into implementing your own plugin system ( like me ) or finding one that is viable for implementation in your project ( possibly like me ).

These resources highlight one reason why there is not a standard Python plug-in framework: there are a variety of different capabilities that a user may want, and the complexity of the framework generally increases as these new capabilities are added

http://wehart.blogspot.com/2009/01/python-plugin-frameworks.html