Short version: how to view the geolocated molecules:
- install the Layar browser
- be in Cambridge
- look for the "cambridgemolecules" or "Cambridge Molecules" layer
Longer Version 
Firstly, install the Layar browser - . This works on the iPhone 3GS or 4, and many Android phones (although I can't find a comprehensive list of which ones).
Now, you have to find the correct layer. It's called "Cambridge Molecules" or "cambridgemolecules", and should appear in the list of available layers. This part can be a bit tricky, and hopefully will improve once the layer has been tested and "Approved"