The PySide project provides LGPL-licensed Python bindings for the Qt cross-platform application and UI framework. PySide Qt bindings allow both free open source and proprietary software development and ultimately aim to support all of the platforms as Qt itself.
Qt is a cross-platform application and UI framework. It includes a cross-platform class library, integrated development tools and a cross-platform IDE. Using Qt, you can write web-enabled applications once and deploy them across many desktop and embedded operating systems without rewriting the source code.