As you will all remember Cris was talking about NFC on Monday. Even though this technology is 5 years old in terms of public release, it is yet to extend itself beyond the early adopters user groups. There are many rumors about it being bundled into the iPhone 5 (the same was rumored for the 4S, so set aside a grain of salt).
Here’s the link
But what are the alternatives. What can be done with smart phone magnetometers? Is Wifi triangulation enough. What can be done with a Wifi address?