Because I wanted to test internet telephony I downloaded Skype and tried to get it to work on my Kubuntu system. Unfortunately, the Skype version is only 18.104.22.168, and it does not work well with arts :( That is, using artsdsp it crashes with segfaults whenever I start even a chat, let alone a phone call. This could be worked around by disabling sound in my KDE session, and then the /dev/dsp is open again.
Better even, I bought a USB telephone yesterday: a reasonably cheap Tiptel 115, with Skype support. Kubunty breezy recognized the USB device, added a /dev/dsp1 and after running alsamixer to raise the sound levels, it seems to work fine, though did not have an actual phone call yet :) I enabled KDE sound again, which is in the first device, and Skype runs on the second. No more segfaults it seems.