The TurboGears project github.com/TurboGears/tg2 has been one of the most used Python Web Framework for nearly 10 years, used in big projects like Sourceforge.net and Fedora.
You can find some good info related to TurboGears at fullstackpython.com/turbogears.html
It's currently nearly a one man effort. So anyone interested in working on an OpenSource Web Framework is welcome at contributing any idea or improvement, from documentation, bug fixes or minor and major features.
The framework recently underwent a major rewrite of its configuration system and a lot of effort is being invested in updating the documentation accordingly.
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