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MapKit

See MKMapView tutorial for Google Maps latitude and longitude.

See iPhone Dev SDK: Map Kit and MKMapView.

See iPhone SDK 3.0 - Playing with Map Kit

and iPhone SDK 3.0 - Playing with Map Kit - Part 2.

See Stack Overflow: MKMapView and setRegion:animated: not updating the map visuals.

See MKMapView Zoom and Region.

Also see GoogleMaps.