From the Windows Vista Blog:

It’s important to emphasize that while Windows Vista has the necessary infrastructure to support commercial content scenarios, this infrastructure is designed to minimize impact on other types of content and other activities on the same PC.  For example, if a user were viewing medical imagery concurrently with playback of video which required image constraint, only the commercial video would be constrained — not the medical image or other things on the user’s desktop.  Similarly, if someone was listening to commercial audio content while viewing medical imagery, none of the video protection mechanisms would be activated and the displayed images would again be unaffected.

This is key to me, the OS has support, but it is compartmentalized in it’s reach and effects. The real engineering challenge is to create such a system such that the OS and hardware ecosystem remains open. The comments also demonstrate that many still are confused by the initial poor examples and hyperbole. For example:

Handing over complete control to the RIAA/MPAA and allowing them to have the final say on what a Windows machine can and cannot do is completely unacceptable. I don’t care if an exploit has been found in my drivers, unless it’s to do with security in the sense of someone being able to compromise my machine I don’t expect to see driver revocation just to satisfy some lawyer.

First, they only have control over thier own content. Second, even if the driver is revocated, the only ability you lose is the ability to see thier content.