Every linguist will tell you that language is always mutating and any dictionary is a biased snapshot of how language is actually being used. The same is true for geography. Locals always know the quickest routes, the shortcuts, the bike-friendly streets. Top-down approaches like Tele Atlas and Navteq can miss these subtleties.
OpenStreetMap is brilliant not only because it's crowd-sourced mapping, but because it allows the crowd to define and create new feature types and place-tags on-the-fly. This means you get a map that shows you where footpaths and dog parks are, but it also means that there's infinite room for connection with other services. Flickr's support for OSM tags is a striking example: http://code.flickr.com/blog/2009/09/28/thats-maybe-a-bit-too...
I should also mention that some of my university colleagues are working on map wiki for cyclists in Minneapolis. http://cyclopath.org It is focused on being a research platform for collaborative map-making.
OpenStreetMap is brilliant not only because it's crowd-sourced mapping, but because it allows the crowd to define and create new feature types and place-tags on-the-fly. This means you get a map that shows you where footpaths and dog parks are, but it also means that there's infinite room for connection with other services. Flickr's support for OSM tags is a striking example: http://code.flickr.com/blog/2009/09/28/thats-maybe-a-bit-too...
I should also mention that some of my university colleagues are working on map wiki for cyclists in Minneapolis. http://cyclopath.org It is focused on being a research platform for collaborative map-making.