Safari on iPhone Graphics, Media, and Visual Effects Coding How-To's
These examples come from Apple's developer site.
Apple also created a great example of a 3D flipping transformation: cardflip. I've been trying to reproduce the effect in some of my own demos, but the HTML seems quite picky so far. :-/
I've been having performance problems with animating the CSS opacity property. This page contains some experiments to see what works best on what browser/platform.