Not so long ago I upgraded to KDE 3.1.1. I had mosfet-liquid already merged. Before upgrading kde, i decided to uninstall each kde application and then retry them one by one to see if they would work well with 3.1.1. So, after merging the entire kde-3.1.1, I merged mosfet-liquid-widgets. First time using --usepkg, and then building it from source. Each time, the control center module to configure it was absent. I tried both versions of mosfet-liquid-widgets in the Portage tree, but I get the same problem with each.
Fixed. Deleted /tmp/*, rebooted and restarted KDE and voil
Fixed. Deleted /tmp/*, rebooted and restarted KDE and voilà, all is working again. I get to this because I emerged kdevelop-3.0_alpha3, and it complained about something in /tmp/kde-[user] which was set to wrong permissions. Please file this bug as fixed (it should never have been here :) )
Ok, done