PyQt4 is a toolkit for creating GUI applications. It is a mix of Python programming language and Qt library.
The biggest advantage is that QT and Python work on all major OS – Linux, Windows, MAC OS, so once you make your application it can run on all the three platforms.
Developers can choose between GPL and commercial licence. Previously, GPL version was available only on Unix. Starting from PyQt version 4, GPL licence is available on all supported platforms.
The tutorial is here: http://zetcode.com/tutorials/pyqt4/ it’s step by step introduction to Qt framework and at the end there is example of Tetris game made with PyQt4