Some DRM systems have started to use rootkit technology. Rootkits are normally associated with malware but in this case a rootkit is used to enforce the copy control policies of audio CDs! DRM software restricts the user's ability to make copies of a record and for that reason uses technology that prevents removal and modification of the software. Sony BMG is currently using a rootkit-based DRM system on some CD records sold in USA. As it looks, this system has been in use since March 2005. Some test purchases for Sony BMG records from Amazon.com confirmed that they contained this technology!
Not a good way to go in my opinion! And there are some rumors of malware already, looking to "re-use" that technology!