Wikipedia
PyGTK is a set of Python wrappers for the GTK+ graphical user interface library. PyGTK is free software and licensed under the LGPL. It is analogous to PyQt/ PySide and wxPython, the Python wrappers for Qt and wxWidgets, respectively. Its original author is the prominent GNOME developer James Henstridge. Today there are six people in the core development team, with various other people who have submitted patches and bug reports. PyGTK has been selected as the environment of choice for applications running on the One Laptop Per Child systems.
PyGTK will be phased out with the transition to GTK+ version 3 and be replaced with PyGObject, which uses GObject Introspection to generate bindings for Python and other languages on the fly. This is expected to eliminate the delay between GTK updates and corresponding language binding updates, as well as reduce maintenance burden on the developers.