Layar: Augmented Reality and GIS

Via Digital Urban I learnt of Layar which is a service for mobile devices that shows information using tools that sense direction and location. I'm not sure how successful this particular service is going to be but IMHO services like this, which add GIS data to normal views via Augmented Reality, are going to be huge.

Why? I think that the fall in popularity of Second Life vs Twitter shows us that the mundane (being able to read bits of text about other's lives) can be incredibly compelling.