Comment 3 for bug 920542

I can't predict the kind of creative uses we might find for more than two images. However, it's already possible and useful for backgrounds alone to use multiple images.
<http://www.css3.info/preview/multiple-backgrounds/>
<http://event-horizon.kicks-ass.net/cargo_bay/css3_multiple_backgrounds/>
If you add a logotype on top of that, you're already using three images, not two.

Ideally, I think the form would dynamically add upload fields as you need them. Specify one file and it adds a second field, specify a second file and it adds a third field, choose "Remove" and the associated upload field disappears too, etc.