WxPython is a very cool tool, written by RobinDunn in Portland, that makes it possible to do Windows programming in Python, and it's cross-platform too.
SteveHowell and AdamFeuer are using wxPython on the WikiOutliner project. One of the pieces is an editor implemented in wxPython. You can actually write an editor in a so-called scripting language, and it runs just fine.
From JonothanFarr:
My first experience with wxPython was actually on a project that turned out not to be well suited to a Python implementation because I needed some real time graphing. So I just converted all of my wxPython code to C++ wxWindows code, practically directly! It was very straightforward except that I had to basically reimplement something similar to Sam Rushing's asyncore/asynchat modules to provide wxWindows with the asyncronous networking support I needed. Python was a practically invaluable prototyping tool on that project. By the time I was writing C++ code, the design was already quite stable and efficient, so the code just all fell right into place. To me this prototyping ability is another strength wxPython has over some other GUI frameworks.
Has anyone used wxDesigner? It's a screen painter tool for wxWindows, and it can generate wxPython code.