Easyjet recently announced that it will be deploying iBeacon technology in a number of key European airports, to help its customers on their journey from drop-off through to the aeroplanes. iBeacons enable mobile devices to discover their position - and are typically applied indoors, where satellite positioning systems such as GPS are unavilable.
The iBeacon technology, based on Bluetooth Low Energy (BLE), has been advocated by Apple as a major advance for retail outlets. In hardware terms iBeacons can take the form of small pucks which can be programmed with a location and attached to a wall or post, e.g. with adhesive. By informing nearby devices of their position, the ibeacons enable applications to exploit context to make things easy for consumers. In the airport example, an ibeacon close to a security checkpoint might prompt air passengers to get their boarding passes ready to be inspected.
More details on the Easyjet plans can be found in this Mobile Marketing Magazine article.