Hi, This page: http://userbase.kde.org/Troubleshooting suggests that application specific troubleshooting should go on the application page. I had this problem already twice so I though it might be useful for others. I'm new to this wiki - would it make sense to have a specific Troubleshooting section?
Problem: Dolphin's menu entries 'View - Additional' and/or 'View - Panels' are empty although nepomuk is enabled in System Settings.
Solution: Rename the folder '~/.kde4/share/apps/dolphin' and restart dolphin. This will purge your dolphin customizations but the entries should be back. This happened to me after an upgrade from KDE 4.4 to 4.5
KDE UserBase Wiki 