Don't know if this has any security relevance ( I'm sure there are some implications ) but...as a wireless issue I thought it belonged here...

Now, a New-York-based start-up company, Navizon, offers a better solution, with its peer-to-peer wireless positioning system which relies on dynamic databases always up-to-date. Users need a free piece of software and a GPS device or a WiFi and/or Cellular enabled Pocket PC PDA. When you're walking or driving, you're able to get your exact location in real time, and companies can send you messages about a restaurant of a film opening near the place where you are.
http://www.mindjack.com/relay/2005/0...-service.shtml
Mindjack - Daily Relay