Nice article here:
A volunteer-led project to create an open-source map of the entire earth, calledOpenStreetMap, has amassed over 200,000 contributors since its inception, the founder announced in a blog entry.
The project has attracted over 100,000 users since last March alone, noted founder Steve Coast. He predicts that, given this rate of growth, the contributor base will reach a million by this August.
I don’t want to be a pessimist, but these projections are nonsense. You will be more looking at 400 000 maximum at the end of the year. So far only 10 000 more contributors signed up in January. There is de facto no exponential growth, unless you start a big marketing campaign.