Early this year, Nokia/Trolltech changed the Qt license from a dual-licensed model (GPL/proprietary) to the more permissive LGPL. But the existing Python bindings for Qt are made by a small company named Riverbank Computing who decided to stick with Qt's original license.
To fix this, Nokia has launched [PySide](http://www.pyside.org/) to make Python bindings available with an LGPL license. From the [ArsTechnica article](http://arstechnica.com/open-source/news/2009/08/openbossa-announces-new-lgpl-python-bindings-for-qt.ars):
> Python and Qt have the potential to be an extremely compelling solution
> for cross-platform rapid application development. The PySide project will
> address the licensing problems posed by PyQt, but it will also have to
> simplify cross-platform deployment and resolve other technical challenges
> in order to really gain traction.
I developed a GUI using PyQt a few years ago and must say that it was the nicest platform to write a GUI in that I have experienced. Qt has an incredibly rich cross-platform toolkit and Python is a great language to work with. Too bad Nokia could not reach a deal with Riverbank Computing; I can't imagine using PyQt once PySide is available on all the platforms required.
By the way, part of the PySide project is a [Binding Generator](http://www.pyside.org/home-binding/binding-generator/) which can be used [to generate bindings for *other* high-level languages](http://www.pyside.org/home-binding/). Hmm.