It gets even stupider for Sony - in their quest to protect their copyrights, they apparently violated LGPL license terms:
The spyware that Sony installs on the computers of music fans does not even seem to be correct in terms of copyright law.
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. A computerexpert, whose name is known by the redaction, discovered that the cd "Get Right With The Man" by "Van Zant" contains strings from the library version.c of Lame. This can be conluded from the string: "http://www.mp3dev.org/", "0.90", "LAME3.95", "3.95", "3.95 ".
I guess when the question came up - "should we be stupid, or just incompetent?" - their management said: "Let's do both!".
Update: More evidence of the hole digging at Sony here.