A popular feature in other OS's and one quite often requested in Linux, is the ability to cycle through a directory of images as your desktop background. Gnome and therefore Ubuntu actually do support this already and have for a long time, however its not easily configured in the GUI like setting a static wallpaper is.
If you go to your appearance preferences and change your background, you may notice a stack of images. This is the 'Cosmos' wallpaper. It is an XML file containing the paths to multiple images. To make your own slideshow, you need to copy this XML file and edit the image paths to the locations of the files you wish to display. Simple enough when you know how to do it, but a bit tedious to say the least.
Today I will show you step-by-step how to create and apply your own wallpaper slideshow, and to make it really easy for you I have created a utility to automate the process.
To use my program for automating this process:
1) Download 'Wallpaper Slideshow'
2) Extract the 125178-wallpaper.tar.gz
3) Double click 'wallpaper'
4) Click 'Run'
5) Select folder containing your pictures
6) Change the time to display each image and transition time (Optional)
7) Click 'OK'
Hopefully Gnome will incorporate a similar utility directly into the Appearance preferences in future release.