Apple Map Links

http://maps.google.com

The maps URL scheme is used to show geographical locations and to generate driving directions between two points. If your application includes address or location information, you can use map links to forward that information to the Maps application on iPhone OS and the Google Maps website on other platforms.

Application homepage: http://www.apple.com/iphone/iphone-3gs/maps-compass.html
iTunes link:
HTML Link example: <a href="http://maps.google.com/maps?q=cupertino">Cupertino</a>
Native application URL string example: http://maps.google.com/maps?q=cupertino
Extended example: http://maps.google.com/maps?daddr=San+Francisco,+CA&saddr=cupertino
Tags:

Note: Unlike some schemes, map URLs do not start with a “maps” scheme identifier. Instead, map links are specified as regular http links but are targeted at the Google Maps servers.

More information on the Apple Developer website