Wengophone says that the audio device is already in use. That's right, because artsd is using it, but my soundcard has hardware mixing, so it's capable of accepting output from many programs at the same time.
I pulled the sources and built Wengophone myself. The same results.
When I try to stop artsd with artsshell terminate, the whole system crashes. WTF?
Sorry, no Wengophone for me. Going back to Skype.