[Rajesh Jain sent me this interesting link] which discusses a project at Nokia called mobile augmented reality application (MARA) that uses mobile phones camera to get information about real world objects by just pointing the camera to them and taking a picture. Such applications are definitely going to emerge and will be useful. This particular one uses a phone with multiple sensors.
 The Nokia research team has demonstrated a prototype phone equipped with MARA software and the appropriate hardware: a global positioning system (GPS), an accelerometer, and a compass. The souped-up phone is able to identify restaurants, hotels, and landmarks and provide Web links and basic information about these objects on the phone’s screen. In addition, says David Murphy, an engineer at Nokia Research Center, in Helsinki, Finland, who works on the project, the system can also be used to find nearby friends who have phones with GPS and the appropriate software.
This is one interesting application of computer vision, databases and internet technologies. It will be nice to see these techniques mature — currently they are in early development.