I'd stress the point that we have seen A rootkit exposed, who can say if there are more than one in existence now (or not)?
It is worth noting here that Sony didn't actually write the rootkit or copy protection software. A small UK-based company did that.
Much like some of the earlier protections which froze Macintosh PCs, could be defeated with CD markers and didn't work in some high-end audio equipment, I get the impression that the music companies did not understand the inherent limits of the technology.
I was surprised how poor a product music companies were prepared to sell when I last brought a CD though (Dido's Life for Rent). The CD did not work with Windows Media Player, or iTunes (and the supplied custom player was absolutely awful). The quality of the digital audio was perceptibly poorer than that of the CD audio. The thing that really irritated me though was how unclear the labelling on the CD case was. A tiny little logo which implied that support for car audio players , PCs , Macs etc. was "<100%". I wonder if I could have raised the issue with the Trading Standards Agency?
The upshot of this was that I went to iTunes Music Store for my next purchase and found it cheaper and more convenient than buying CDs.