The visualization installation consists of a large array of Apple Cinema Display monitors mounted together on a wall, showing what looked to be some sort of "pulsating" canvas. The canvas itself is made up of 20,000 icons, arranged by color, representing many of the apps available in the App Store. Apparently, when someone purchases a particular app, the according icon pulsates with a 5 minute delay, creating a mesmerizing visual effect.
TechCrunch has a few more high-rez pictures, or you can watch a short video below.
Image taken from liquidx @ Flickr.