How can I manage audio volumes sanely in my Android app?

Got another suggestion via Google Groups that is the platform integrated solution I was looking for and works fine:

Please don’t handle the volume keys
yourself – it is almost impossible to
guarantee that you won’t break the
behavior of the volume keys.

Call this API in your onCreate():

setVolumeControlStream(AudioManager.STREAM_MUSIC);

This tells the AudioManager that when
your application has focus, the volume
keys should adjust music volume.