Airplay was first introduced by Apple with iOS 4.2 release. It was the feature of iPad at first while expanded to all iOS devices in iOS 4.3, which allows you to wirelessly stream movies/music on iPad, iPhone or iPod touch to Apple TV for a much larger screen experience. The Airplay feature was only for original Quicktime Player embedded in iOS 4.2 and later applied to third-party player apps like AVPlayer or OPlayer. Now, Apple even enhances the Airplay feature in iOS 5, and rename it Airplay Mirroring.
This Airplay Mirroring enabling users to wirelessly transmit the on-screen content of the device to an Apple TV for display on a television. The iPad 2 currently supports display mirroring via a Digital AV Adapter that provides a wired connection to a TV via HDMI.
One of the criticisms of the wired mirroring has been the cumbersome nature of the dongle and cable hanging off of the end of the device, particularly when it comes to games and other apps that require movement of the device for input purposes. Consequently, AirPlay Mirroring should be a significant boon to those looking to display their iPad content on the larger screen, especially if lag is minimal. This feature endows the iPad 2 with the ability to wirelessly mirror all video on the screen of the device to an Apple TV 2. No longer is mirroring just enabled in a few apps here and there -- anything on your iPad 2 can be blasted to the big screen with a few taps.
Here is a short demonstration of the new Airplay Mirroring in iOS 5: