The cool browsers support radius corners, but Safari supports CSS transformations that allow developers to scale, skew, and rotate objects on the page like we’re used to doing in PostScript. And better than that, we can animate those transformations over time — all without any JavaScript.
Fire up Safari or Chrome and mouse over the examples here. The screencast at the top is from the menu on that page. There are, obviously, better uses for these transforms, but it’s easy to see it at work there. Also see this screencast. It shows a rendering error, but it’s a better use of the tech.
Now kick it up a notch with 3d transforms. They only work on the iPhone and iPod touch for now, but they’re quite nifty. See these examples: one, two. Paul Bakaus offers more detail, and Matthew Congrove offers this example of flick navigation.