SWT
There is an extensive page on SWT on the Eclipse platform homepage.

Python GUI Development

Python always had support for the Tk toolkit via its module tkinter.

Another good, free choice is the wxPython binding to the wxWindows toolkit.

If you don't mind paying a moderate license fee for a very nice IDE, BlackAdder with its visual editor for PyQT development might be a good choice.

The Standard Widget Toolkit for Python

PySWT provides a Python binding to the Eclipse Standard Widget Toolkit (SWT). This binding allows Python developers to write graphical user interfaces portable to all platforms supported by the SWT, while maintaining the native look&feel of each platform.

Please check out the project page at sourceforge.