Quite an interesting approach to mapping, and it sounds pretty useful for the intended purpose. Conversely, I'm in the 'Lazlo Hollyfeld' boat of wondering what the purpose might be for the actual goals of Facebook, which isn't connectivity and internet altruism, but generating revenue. In this regard, I wonder what comes next, because looking at evidence of human activity will probably relay more rural and dirt-poor settlements than ones with disposable 'leisure time' and monies.