Last weekend, I spent Sunday upgrading Ubuntu to 9.10 (Karmic Koala).
When I'm at my desk, I plug my desktop speakers into my laptop. Out in the living room, obviously, I don't.
Last night, when I unplugged my desktop speakers, my laptop speakers didn't kick in.
This morning, after a kernel update and reboot, THE LAPTOP SPEAKERS KEEP PLAYING WHEN SOMETHING IS PLUGGED INTO THE JACK. Desktop speakers, headphone, whatever.
And, for the record, their sound quality REEKS (as my gaming group will tell you without hesitation).
Ah, well. I was planning to upgrade the OS to 10.04 (Lucid Lynx) this weekend, anyway. Hopefully, it's a release-specific glitch.