Well, I still don't understand WHY I need a semantic desktop at all.
My KDE taskbar doesn't work correctly on KUbuntu 11.10, but I can share it over the network (what for?!?!). KDE 3.5 had wonderful multi-desktop support but now I not only have multi-desktop, but multiple activities each with its own widget set.
Then there's a question of usability. Nepomuk allows me to reassure myself that all my music is in ~/Music, but there's no way to find which program uses a certain keyboard shortcut.
So, what are the use-cases for the whole 'semantic desktop' thingie? I have yet been able to find one.