NSA granted internet location-tracking patentthe NSA was granted patent #6,947,978 on Sept. 20, 2005. this geo-location patent, invented by stephen huffman and michael reifer, with the NSA as it's assignee differs pretty significantly from other geo-location patents by Digital Envoy and Quova/Microsoft in that it relies on measuring the latency between a bunch of different internet locations to build a "network latency topology map." in theory, an internet address at an unknown location could be identified by measuring how long it takes computers at known location to connect to the unknown one. i'm really not sure how it will stack up against the more "normal" technologies but at least i can say it's a different approach. cnet has an article on this.
and if you care, you can see one of the more "traditional" technologies in action as a CFC here.