Not really a bug.
When I first got my dm9, took it to work as you do to show it off. Thought I'd list to some music, headphone plugged in etc. Still got sound through the speakers.
I did then install Ibex, at first, plugin in the head phones killed the speaker sound. Great I thought, then, I lost sound in the right channel of the head phones, tried a different set still the same. Then I noticed that if you only partly pushed in the jack sound returned to the right channel. Thinking this was faulty hardware I restored the dm9 back to factory defaults.
Guess what, sound working properly with du8.04, well apart from still having the sound from the speakers while the head phones are plugged in. I thought I could live with that by just turning down the speaker volume in the sound applet but for some strange reason, speaker volume gets reset to maxium on rebooting, not good, now that's a bug. I have found though that you can mute the speakers in the applet and that setting is remember on reboots so not all bad.