Several years ago we had a product called MapPoint Location Server. The concept was that we could tie into phone networks to find and/or track the location of people via their cell phones. The product itself was nothing more than a server client application that proxied calls between different cell phone networks and MapPoint Web Service. Locations could be rendered on maps on a desktop application (sort of like a dispatch) or on a mobile device (for the person trying to find themselves or others - which reminds me I could use something to help find myself, but, I digress). Because of the E911 initiative, carriers were required to be able to located cell phone users within a certain radius (I believe it was 1 mile). We decided to spin this into a business application. Now, with cell phones integrating GPS the accuracy is greatly improved so a similar project has sprouted up at Microsoft (MapPoint Location Server was shelved). In the US, I'm still seeing resistance of the carriers to open up access to the GPS API, but maybe with the right pressure we can gain access and create some valuable applications using the GPS chip. Anyway, the WhereAmI Project is the latest attempt to use tracking capabilities for finding friends. Once you've found those friends you can find things around them such as ATMs, Bars and Shopping Malls. We hope to see this exposed in a platform someday, but for now we'll just have to keep an eye on where Nagi Babu Punyamurthula (the creator) and his friends are.
In the meantime, you can always download our mobile client in case you need to find yourself (as I do). There's an interface for adapting the Pharos GPS 500 Sirf III device that comes with Streets & Trips and MapPoint.