Portland airport tells you where you are: Nigel Ballard of Personal Telco Project wrote in to note that Portland International Airport's new free Wi-Fi network has a page showing where you're connected and also showing the extent of the installation and its coverage area.
It's a neat demonstration of how to connect location with service. I know there are many companies working on putting time, space, and Wi-Fi together--such as Ekehau--and this is nice, clean example of this utility.