Google Maps for iPhone 1.1
Google Maps for iPhone 1.1 is an improvement over version 1.0 in that it can now access contacts from your Google account. However, it only does this via search (no browsing), and it still can’t access the iOS contacts database.
Update (2013-03-13): It’s worth reminding that, even better than Google Maps adding iOS Contacts integration, would be for Apple to let iOS users choose the default maps app. Then you could use any existing contacts app with Google Maps.