The code is pretty simple.  Just something like:

CLLocationManager* locationManager = [[CLLocationManager alloc] init];
locationManager.delegate                = self;
locationManager.desiredAccuracy = kCLLocationAccuracyBest;
[locationManager startUpdatingLocation];

The delagate is just two functions:

- (void)locationManager: (CLLocationManager *)manager
didUpdateToLocation: (CLLocation *)newLocation
fromLocation: (CLLocation *)oldLocation
{
}

- (void)locationManager: (CLLocationManager *)manager
didFailWithError: (NSError *)error
{
}

If you put this in your code, you magically get a prompt that looks like this.  “Untitled” is the name of my application.

Location Request for "Untitled" application

Clicking on the Help icon, you get the following:

Help screenshot

The network requests goes to mac-services.apple.com.  The good news is that it is over a secure network channel.  The bad news is that the content is also hidden from inspection.  (eg.  since this is close source, Apple could be passing anything.  The thing that worries me is that it might be passing the application name which would give unfair Apple insight into what applications are popular).

The accuracy is pretty good — it places me at the building I am working from.  Now where is the support for Geolocation in Safari?