Most of these theories see the city as a purely physical space. So, how do these theories hold up in the era in which the city is saturated with media networks such as, to name just a few, GPS, WIFI, UMTS, HSDPA, GSM? Now that mobile and locative media change our interaction with our environment, no longer do we just experience the physical city itself: we SMS and chat with distant friends who in our minds are near at hand. We can inquire about our location, or leave virtual graffiti for those who’ll pass by after us. We can withdraw our attention from our actual surroundings, and into the mediated spaces of these networks. Or we can actively engage with our surroundings through the screens of our mobile phones.”

http://www.receiver.vodafone.com/locative-media-and-the-city