In a new Knowledge Base document, Apple encourages users who "experience unexpected results when tapping the Location button in Maps" to submit WiFi location information to Skyhook -- the service used by the iPhone's quasi-GPS function -- in the hope of establishing better accuracy.
Submitting an access point to Skyhook is easy. Navigate to this page, then enter the city you're in, or better yet the address and city, then click "Map It!" Refine the location to an exact point by dragging the marker. The latitude and longitude will be automatically generated. You then need to discover the MAC address for the WiFi point associated with the designated location.