A visitor to this site wrote in and pointed me to a project he's working on called Pangaea. This is a reverse geocoding application that uses google latitude. I actually looked for something just like this while building the clock since I wanted something more automatic than the Twitter feed to update status. Pangaea lets you set coordinates and radius as a named location. It checks your Google Latitude public feed and figures out which location you're in and feeds the name back in a custom feed. I really like this approach and plan on incorporating it into my clock code.