Apple introduced Dashboard today. Dashboard is an addition to Exposé which gives users quick access to mini-applications called Widgets.
Apple adds a bit of flare to the widgets by taking advantage of the Core Image technology in Tiger to take advantage of some real time effects.
Two examples from the current implementation of Dashboard include:
Ripple Movie (312k) - When current widgets are launched, they appear with a water-ripple effect on the desktop.
Flipping Sticky (159k) - To change the color or font preferences of a sticky note, you simply click on the rotate button and the sticky flips around to offer preferences controls on the back.