Qt is a high-performance, cross-platform application development framework. It includes a C++ class library and tools for cross-platform development and internationalization. More importantly, Qt is the foundation on which KDE is built. From its inception till now, Qt has been released under a variety of licenses such as Qt Public License, GPL v2, and even a commercial license for developing for Windows platform (More here).
Yesterday, Trolltech's CEO Haavard Nord warmed the hearts of millions of Free software enthusiasts when he announced at the KDE developer conference that Qt will henceforth be released under a GPLv3 license (even for Windows platform), over and above the QPL/GPLv2 license it holds now.
Here is what Richard M Stallman the president of Free Software Foundation had to say about this news (and I quote) :
Another reason to love KDE even more....
I am very pleased that Trolltech has decided to make Qt available under GPL v3. This will allow parts of KDE to adopt GPL v3, too. Even better, Trolltech has made provisions for a smooth migration to future GPL versions if it approves of them."You can download the GPLv3 licensed packages of Qt3 at the following location.