Core Animation is the secret feature of Leopard. It's been right under our noses all this time.
Apple will use it to goof effect to the UI in Leopard to surpass Aqua and also Vista.

Watch and see.

Interesting typo aside, I think you've hit the nail on the head. I'd be willing to bet that the Core Animation is heavily used with a substantial remake of the Finder. If you look at the Leopard beta versions out so far, Apple has not made a substantial update to the Finder yet (aside from stuff like QuickView, which is somewhat separate). This is certainly pointing to the fact that a Finder update is one of the "Secret Features".