I've just installed Debian Testing 64bit with KDE 4.7.4. I'm very happy to be back using Debian again after a few years of non linux use and the last couple of weeks trying out OpenSuse and Fedora, both with KDE.
I've get everything set up apart from being able to set and save my own wallpaper choice(s).
I copied the images I used on Suse and Fedora into /usr/share/wallpapers as root using konsole, but they don't appear in the choices under Desktop Settings - Plasma Desktop Shell. All that is there are the wallpapers that came with Debian. Mine are definitely there when I check the folder via Dolphin.
I can click on Open and set my own image but as soon as I log out or reboot I'm back to the default choices again.
I also put the images I want to use in ~/.kde/share/wallpapers as well, in OpenSuse and Fedora that's all I had to do to get them to be listed as choices. But they still don't show up. If I click on Open from Desktop Settings-Plasma Desktop Shell and navigate to that wallpapers folder in my home directory, the folder shows the previews but when I open it it looks empty, which it isn't.
I can install new wallpapers via the Get New Wallpaper button but I can't use my own as I did with out any problem in OpenSuse and Fedora.
Permissions look correct so I'm a bit lost. If anyone can help I'd appreciate it.

I think I've solved it. It was indeed a permissions problem.

I thought you were using some other word until I looked that up.

Just started up again after overnight shutdown - yeah, back to only the default wallpaper.
Just one KDE niggle too many, here comes XFCE.