Here is a link to Michael Foord talk at Pycon 2009 in Chicago about functional testing of desktop applications:
Functional Testing of Desktop Applications
Many advocates of unit testing believe that testing desktop (GUI) applications is so difficult as to not be worth it. Not only is it possible, but 'functional testing' (testing an application from the point of view of the user) is an important part of an agile development process.
I watched it yesterday and it is very good!