I had the honour and pleasure of starting this thing. I see the Wikiproject article was created 09:15, 13 February 2005. I made some convention for adding the lat/lon coordinates, which then linked to a small website that had proper link to various map resources (this was before OpenStreetMap). I documented it, then manually added links to a few articles, just to have some critical mass to start it off. After that, it kind of caught on, and now we have a million articles with coordianates, and a whole lot of super mobile phone apps and other applications I could never have imagined.
So you can bash WIkipedia all you want, but to me, this really shows the immense power of Wikipedia.
This picture really summarises how incredible this project is. Note the size of the sub that they use as a tow vehicle.