I think the title is self-descriptive. Tested on Kubuntu Jaunty Beta and RC LiveCD sessions.
It isn't working on a installed system either :(
It seems it happens with existing users only. Did you perform an upgrade or a clean install?
I think I installed Kubuntu from the BETA.
This is fixed in KDE 4.3
Bug watches keep track of this bug in other bug trackers.
It isn't working on a installed system either :(