Pylons is a modern web framework that was written in the Python programming language and follows the model-view-controller design pattern. The framework significantly facilitates the creation of complex web applications. Pylons makes extensive use of the Web Server Gateway Interface, which is an interface between web servers and web frameworks for the Python programming language. This makes it possible to outsource functionality to separate modules. Pylons is heavily influenced by Ruby on Rails.
You can find more information on the project page.