We could be witnessing the death of unencrypted MP3 as a mainstream music sharing format and the dawn of an era of universal access control for digital media. Napster, for all intents and purposes, will not be operating in any recognisable form for very long. And nobody really thinks that Universal, one of the most vehement opponents of unprotected file formats, will allow its recently-acquired EMusic subsidiary to keep selling standard MP3s. (Given that Universal and fellow 800-pound gorilla Sony have a fascistically copy-controlled music diestribution system in the works suggests that EMusic will be subsumed into it, becoming part of the new world order of end-to-end access control.)
Of course, this brave new world will only be available under Windows and on hardware-based trusted clients. Linux, for example, will never play any secure formats, as there is no way to guarantee a secure media path at the bare-metal level if the filthy thieving user can modify the kernel to divert data as it goes out to the sound card or do something similarly evil and reprehensible.