PDQt is licensed under the terms of the GNU General Public License (GPL) v2 and the source code is freely available. The front-end was adapted from pdPod, a front-end built upon Nano-X, which is a part of iPodLinux.
There is a PDQt documentation video.
You will find the development page with an explanation of the history of the program and it’s concepts at http://wiki.github.com/wincentbalin/PDQt/. The source code repository resides at http://github.com/wincentbalin/PDQt/. Please use it for possible bug reports too.
Downloadable files as well as the source code reside here.