wxGlade is a GUI designer written in Python with the popular GUI toolkit wxPython, that helps you create WxWidgets/ WxPython user interfaces. At the moment it can generate Python, C++ and XRC (WxWidgets' XML resources) code.
As you can guess by the name, its model is Glade, the famous GTK+/GNOME GUI builder, with which wxGlade shares the philosophy and the look & feel (but not a line of code).
It is not (and will never be) a full featured IDE, but simply a "designer": the generated code does nothing apart from displaying the created widgets. If you are looking for a complete IDE, maybe BoaConstructor or PythonCard is the right tool.
Project website: http://wxglade.sourceforge.net/