The noble audio guide has been around for decades. A truly wonderful device. Below is a photo of the 1951 Stedelijk Museum audio guide (excluding battery) first meant for hearing impaired visitors.
This is a familiar piece of equipment that many of us will have lugged around a museum on a school trip or family day out.
Throughout the 1980s and 90s, they hardly changed at all. Not in their technological capabilities, nor their appearance. Now we are used to being able to download audio tours straight onto our iPods or smartphones.
Some museum and gallery visitors even use apps such as Layar to enter the world of Augmented Reality. Point your phone at a building, painting or artefact and it will superimpose Wikipedia information, Flickr photos or Youtube videos.
The next step up may well come courtesy of Project Glass, from Google. Incredible.