Check out this post by Gizmodo, showing off part of Apple’s display at WWDC:
Apple stationed a little bit of eye candy in the Moscone Center lobby: a 5x4 matrix of Cinema Display monitors, set adorned with thousands iPhone app icons. The twist? Whenever someone purchases the app, it pulsates.
Apparently it’s not quite real-time, but the effect is extremely slick. Grouping the icons by their approximate colors creates a subtle gradient, which is a nice touch.