Interesting article. My last name really is Church. It's impressive how much functionality developers can build using the browser's native Geolocation API.
One area I'd love to see more developers explore is the transition from outdoor location services to indoor navigation.
Finding a building using GPS is relatively straightforward, but guiding someone to a particular floor, department or product aisle introduces a completely different set of challenges.
There's a lot of potential for making these experiences more seamless, especially for applications that combine outdoor and indoor destinations.
Great example of turning a simple browser API into something useful.