So I just did an dist-upgrade of my Kubuntu 10.04 system running KDE 4.4 to KDE 4.5. Upon a reboot, there was a problem. I had no desktop. Just a blank black screen.
So I began to dig around to see what the problem was.
The solution was to install the package 'kubuntu-desktop' which triggered a group other packages to be installed (such as kdebase-workspace-bin, for example). This group turned out to have everything I was missing. I have NO idea why these packages were not install during the upgrade, but this has been a weird one. (During the past few days, when checking if I had any updates, I was presented with what looked like have available dist-upgrades to KDE 4.5, which would have resulted in some strange installations AND removals had I applied it. I can only assume this was because the packages in the repositories were being updated over a few days and thus the lists had some old and new mixes that didn't jive quite perfectly until all were updated.)
Also, during the install I failed to update the /etc/kde4/kdm/kdmrc file to the newest version (my fingers slipped on the keyboard, if you can believe it). I don't think this was the cause of my problems, but I did manually upgrade that just to make sure.
Noteably ktorrent is not available in the Kubuntu PPAs because of a version dependency. Strange. Hope they fix that soon.