Source: http://gizmodo.com/5642578/point-an-iphone-at-the-sky-see-augmented-reality-info-as-planes-fly
Plane Finder AR adds a layer of augmented reality to its previous (and free) Plane Finder app, now charging $3 for the privilege of seeing the flight number, speed, destination and other such details of overhead planes.
The same developer is making a name for itself in transportation apps, with its Airline Finder acting as a guide to all the various airline planes in the world; Ship Finder showing real-time movements of our aquatic vessels; and the real-time Plane Finder and Plane Finder Free apps, which only has $5 and detailed aircraft information on each plane between them.
This latest one, Plane Finder AR, displays augmented reality information on the iPhone 3GS and iPhone 4's screens, when pointed at a plane in the sky. Little thumbnails appear, highlighting the flight number, speed, altitude, last port of call and destination, and how far away it is from you.
It works by picking up the ADS-B data from the planes, which is why not every plane the iPhone is pointed at has information to be displayed. [iTunes via Recombu]