Qt is a cross-platform application framework that is widely used for developing software with a GUI but can also be used for non-GUI applications.
http://developer.qt.nokia.com/wiki/PySideDownloads/
Note
If your software does not fully comply with the GPL you will need a commercial license!
http://www.riverbankcomputing.co.uk/software/pyqt/download
Note
The Cocoa framework is only available on Mac OSX. Don't pick this if you're writing a cross-platform application!
Note
Only available on Mac OSX. Don't pick this if you're writing a cross-platform application.
Go to http://www.wxpython.org/download.php#stable and download the appropriate package for your OS.
PyGTK provides Python bindings for the GTK+ toolkit. Like the GTK+ library itself, it is currently licensed under the GNU LGPL. It is worth noting that PyGTK only currenty supports the Gtk-2.X API (NOT Gtk-3.0). It is currently recommended that PyGTK is not used for new projects and existing applications be ported from PyGTK to PyGObject.
Tkinter is a thin object-oriented layer on top of Tcl/Tk. It has the advantage of being included with the Python standard library, making it the most convenient and compatible toolkit to program with.
Both Tk and Tkinter are available on most Unix platforms, as well as on Windows and Macintosh systems. Starting with the 8.0 release, Tk offers native look and feel on all platforms.
There's a good multi-language Tk tutorial with Python examples at TkDocs. There's more information available on the Python Wiki.