New nightly builds of Safari's bleeding-edge doppelgänger, WebKit, are getting some new support for CSS animations -- support that's already available in MobileSafari.
The animations, which include a falling leaves effect, a way to simply animate objects sliding across the screen, and a "pulse" effect (described as "the new <blink>") are all supported by WebKit. The WebKit blog shows code examples about how to use these behaviors in your own sites.
MacRumors's Arnold Kim suggests that Apple may be looking to obviate the need for Flash on the iPhone and iPod touch through the implementation of web tools like CSS Animation. I would argue that while CSS is powerful, getting Flash on the iPhone is about one thing and one thing only: Games.