In a recent article on free software and the Large Hadron Collider I mentioned that here in the United Kingdom The Guardian, a national British newspaper, had founded a campaign called "free our data". They objected to the fact that the Ordnance Survey (and others), funded by the British taxpayer, was charging business and individuals for its cartographic data thus effectively making people pay for it twice. Their campaign is great but until such times as it succeeds an alternative is needed. A free software alternative. Enter OpenStreetMaps.
Google Earth and Google Maps are too well know to require iteration here, but the spectre of proprietary software haunts them. They are not free software. If you want to incorporate any of them into you budding business project and run your software under a relatively permissive licence for others to take up your ideas and improve them you will have to find something else.
Just like Wikipedia, on which it is loosely modelled, OpenStreetMaps is resolutely free software. It is an attempt, by community participation, to map the Earth.