Thanks to Christian Heilmann of Smashing Magazine:
First of all, why is it important to consider physical location on this planet (at this moment) when we develop Web products? There are a few answers to this.
The first answer is mobility. The days of people sitting in front of desktop machines at home are over. Sales of mobile devices, laptops and netbooks have overtaken those of bulky stationary computers in the last few years. The power of processors now allows us to use smaller, more mobile hardware to perform the same tasks. So, if people use their hardware on the go, we should bring our systems to them. Which brings us to the second—very important—point: relevance.
Giving the user content that is relevant to the physical space they are in at the moment makes a lot of sense…