This is made possible by a script found at www.alistapart.com called rotate.php.
- Create a directory under the web server's document root. I placed it under my theme's directory.
- Populate that directory with images.
- Download script and put it in a nice resting place.
- Edit script so it can find your image directory. To avoid editing you can just place the script in the same directory as the images.
- Under your theme's config, for custom logo, instead of a path to an image use the path to the script.
- You're done.