Google Maps provides several useful APIs for accessing data: a geocoding API to convert addresses to latitude and longitude, a search API to provide locations matching a term, and a details API for retrieving location metadata. For many mapping tasks it is valuable to get a large list of locations (restaurants, churches, etc) – since this is valuable, Google places a rate limiter on the information, and encourages caching query results.
He includes the code (both front- and back-end) that you'll need to make the system work. It makes a request to the Google Maps API as usual but then adds a listener with a callback. This takes the latitude/longitude data and runs a "get details" method to get more information. The result is then POSTed to PHP and written out to a file.