This article is worth reading:

Mark's Sysinternals Blog

Sony, Rootkits and Digital Rights Management Gone Too Far -

http://www.sysinternals.com/blog/2005/10/sony-rootkits-and-digital-rights.html

The company that created the DRM software for Sony has issued an update:

"SonyBMG and First4Internet, the companies caught installing rootkit-like software on the computers of people who bought certain CDs, have taken their first baby steps toward addressing the problem. But they still have a long way to go; and they might even have made the situation worse.

"Yesterday, the companies released a software update that they say “removes the cloaking technology component that has been recently discussed in a number of articles”. Reading that statement, and the press statements by company representitives, you might think that that’s all the update does. It’s not.

"The update is more than 3.5 megabytes in size, and it appears to contain new versions of almost all the files included in the initial installation of the entire DRM system, as well as creating some new files. In short, they’re not just taking away the rootkit-like function — they’re almost certainly adding things to the system as well. And once again, they’re not disclosing what they’re doing." - http://www.freedom-to-tinker.com/?p=921