Ben Putman demonstrates a possible navigation option with the Safari iPhone browser that utilizes the proposed WebKit CSS transforms and animations that have been incorporated into the latest release. With an iPhone or iPod touch, go to this demo link.
In thinking of an interesting test, I've created a iPhone Safari 3D navigation menu that you can rotate across a fixed y-axis with touch, allowing you to spin the menu around and see the depth and back of elements. There are also some examples of how animations can be used as you click and the menu unfolds. I also added a lightbox to examine how one might view some photos although it's not really practical in this form.