Comment 1 for bug 671108

Hi,

this is the relevant information that describes the behavior of applications registering for media button events.

http://android-developers.blogspot.com/2010/06/allowing-applications-to-play-nicer.html

So it should be enough to start the default music player once and that will override the media button registration.
Unfortunately I can't test since I can't log in to ubuntu one right now :-(

hope that helps.
Fabian