still the only one

As far as I know, KDE is still the only desktop environment that comes with fully-functioning, automatic, timed wallpaper changing -- and you can have different wallpaper set-ups on different desktops, too. (Enlightenment E17 also has one that I don't like quite as much; whether E17 should be called a "desktop environment" instead of a "window manager" is somewhat debatable, but in any case, its automatic wallpaper changer functions well.)

In openSUSE 12.1, I set it up by going to Configure Deskstop (Personal Settings) > Workspace Appearance and Behavior > Workspace Behavior > Virtual Desktops > Desktop tab. There, I checked the box next to "Different widgets for each desktop." That's so I can have different wallpaper set-ups on each desktop.

After that, I just went to the Desktop Settings for each desktop and set things up. For Desktop 1, under the Wallpaper drop-down list, I chose "Slideshow," set the time interval, and pointed to the directory where my images are stored:

For Desktops 2, 3, and 4, I wanted only one set image, so I went to Desktop Settings, chose "Image" from the Wallpaper drop-down list, clicked on "Open," and selected an image:

I don't know why the devs for other DEs can't implement something like this, but it's one thing about KDE that's head-and-shoulders above all the others. This is in KDE4, but folks were also able to do something similar back in KDE3, so it's nothing new.