The OpenStreetMap module for Drupal will allow users to interface with the OpenStreetMap project to create an open map of the world.

The module will be aimed at localised sites for specific regions, allowing people to edit data already in the OpenStreetMap database as well as add their own information to the map. Because all of this information will be treated as nodes in Drupal, you will be able to build up a local information site based on the information. With the GeoRSS module or KML module you could redistribute this information to other people interested, or do just about anything else with the information that you can imagine.