I'm going to post this all over the various lists...
I updated my Sid install to the experimental KDE 3.4.1 packages from pkg-kde.alioth.debian.org. I switched to init 3 and did apt-get install kdebase, kdeadmin, kdenetwork, kdepim, kdegames.
Now KMenu is empty, I only get the 4 "service" items (Preferences, Quick Browser, etc). All the apps are gone, even though they clearly are still in the system. I tried doing update-menus, either as user and as root, to no avail. I also wiped the ~/.kde directory, still no luck.
Any suggestion on how to fix this?