It turns out that the rootkit contains pieces of code that are identical to LAME, an open source mp3-encoder, and thereby breach the license.
This software is licensed under the so called Lesser Gnu Public License
(LGPL). According to this license Sony must comply with a couple of
demands. Amongst others, they have to indicate in a copyright notice
that they make use of the software. The company must also deliver the
source code to the open-source libraries or otherwise make these
available. And finally, they must deliver or otherwise make available
the in between form between source code and executable code, the so
called objectfiles, with which others can make comparable software.
Sony complied with non of these demands, but delivered just an executable program.
Man… this stuff is unbelievable! Good article on De Winter Information Solution, who also thinks that Sony has to show the Source.
It just keeps getting worse and worse. If you need to catch up to
everything that has been going on with Sony's Rootkit DRM, take a look
at this Boing Boing timeline.