How does the location get updated?
I have written a Java app that runs on my phone. When it's running, it sends location updates to a server that I've also written.
This is then saved in a database.
The webpage you're viewing now queries the last location via AJAX every few seconds, and updates the text, and moves the map. It's as accurate as the GPS on the phone is - +/- 100m to +/- 5m
If you have a mobile phone that supports J2ME and JSR-179, you can do this.
I first got this working on the Nokia N80 (Internet Edition), then I used the Nokia N95, then the N97, and now it's an Android