PyQt4 is a set of bindings for Qt 4, a cross-platform C++ framework used to make graphical user interface (GUI) applications. With the release of PyQt4, Python developers are now able to develop powerful cross-platform applications and deploy them under the GNU General Public License (GPL) or the Qt Commercial License on all platforms that support Qt and Python. We will first briefly discuss PyQt (for Qt 3) and PyKDE (bindings for the K Desktop Environment), and take a look at what has changed in PyQt4. The main part of the presentation will cover the new possibilities that PyQt4 offers developers, including access to Qt's rich text handling features, sophisticated data handling controls, internationalization support, and integration with the Qt Designer GUI design tool.