Without a doubt augmented reality is one of the most exciting developments in mobile/spatial technologies and will, I believe utterly transform our idea of urbanism and architecture in the years to come. There are some great apps like Layar and Junaio which go for a more all-round experience - and then there are brilliant one-trick ponies like Nearest Tube. My vote in these early days is for the one-trick ponies, and it is no surprise that Nearest Tube has become so popular.

If you own an iPhone or iPod touch and you are in London it’s a must!