Google search seems to bear out my problem as being valid and not local to me:
When you connect to a Bluetooth media device (headset or stereo), the controls only work for the Google Music application, and frequently (always?) do not cause anything to happen for any other application.
When I use BeyondPod to play Podcasts, my headset audio controls do absolutely nothing. If I go into Google Music, I can use the controls normally. I haven't investigated to see Google Music has a stranglehold on Bluetooth controls (and thus uninstalling Google Music and using another app will fix the problem) or if the events aren't getting sent to the third party apps at all.