Layar a new app is making the rounds on the web as an example of what can be done with Augmented Reality. Layer is described as the world's first mobile augmented reailty browser. The app accomplishes this through the use of the Compass, camera and GPS embedded within the phone. The app is first available for the Android devices but they are working hard on porting it to other platforms "with a prime focus on the iPhone 3G S.". The iPhone 3G S is the first Apple iPhone to contain a digital compass which is required for such applications.
Source:→ Mac Rumors