An interesting note about Microsoft's up and coming “Zune” player, it seems that the new device will not play DRM-encrypted files made with older DRM technology. For a company that aggressively pushed DRM and promised it doesn't impact “fair use”, Microsoft may have found themselves in a sticky situation when it comes to trying to sell the Zune. Aside from not playing files protected by even their own Windows DRM, there are many other files it can't play:

Microsoft's Zune will not play protected Windows Media Audio and Video purchased or "rented" from Napster 2.0, Rhapsody, Yahoo! Unlimited, Movielink, Cinemanow, or any other online media service. That's right -- the media that Microsoft promised would Play For Sure doesn't even play on Microsoft's own device.
That conclusion was presented by absence of evidence, so there's still a slim possibility Microsoft may make a turn around before it hits the market. That seems unlikely, however, and many people looking to stick with MS for the DRM compatibility may find themselves sorely disappointed.