I've been experimenting with phonon, configuring its output soundcard depending on the applications - my audioplayer used the speakers, my games used the headphone. Unfortunately, the games don't understand any of that stuff and it often didn't work properly. So I turned my internal soundcard off. When I booted up again, I was presented with the following dialog:
That's the first time I saw KDE respond to changes in hardware. Configuration of such stuff has always been something the distribution had to take care of. Some distro's let you manage this by hand (like my Arch), others provide tools like Yast. But we're now moving one step further - integrating this functionality into the KDE libraries, making applications aware of what's going on beneath them. Very cool, that's for sure...
Unfortunately this only works for apps using Phonon. I hope in time, when other development frameworks catch up, something can be found to make this work out of the box with other apps as well.
Oh, and I hope everybody enjoyed Christmas or the other holidays they've had. New year in a couple of days, enjoy that as well and be careful with fireworks ;-)