Apple has confirmed what was already expected. They would ship iOS 6 with their own mapping technology.
It is not clear what would happen to Google Maps. Google should be able to continue offering their Maps application through the Apple App Store though it might get all the system privileges that it had before.
Apple said that their mapping platform would feature deep integration with Siri and Yelp. It would also feature real time traffic data collected from iOS users globally. This is something Google and Nokia do already on their mapping services.
Remains to be seen how good Apple Maps are for the international market. Apple can do well for the major cities in the world. It is the less popular areas where Google is likely to retain their advantage for the time being.