How it works:

Mobile phone
On the Mobile Phone,  a Windows Mobile 6.1 ( HTC Touch Diamond) runs a .NET CF 3.5 application that sends the current GPS-location to the server. This is done every second, or on a chosen interval.

Live tracking application

The server
On the server there is a simple php script that stores the GPS-location and device-id, send by the phone, in a database.

The web-application
The web-application is build in Adobe Flex Builder 3  and fetches the last known GPS-location from the server.
It then  draws a marker on the map and starts updating again.

To get an idea of how it works without me being on the run (and running the gps mobile application) use the simulation mode.
I have recorded two sample tracks, a walking track and a track by car.

Things to do:
Smooth map movement
Select mobile device(s) to show, and zoom map to show all selected mobile devices.
Show (last known) direction, speed, distance, top speed..

(this is partly implemented in the html/javascript version on http://www.arenddeboer.com/liveTracking/)