The other comments about theories of how this works are insightful, and I encourage you to read them. I also wanted to point out the Facebook acquisition of my

The other comments about theories of how this works are insightful, and I encourage you to read them. I also wanted to point out the Facebook acquisition of mysterious Kuala Lampur startup Octazen: http://www.quora.com/Why-did-Facebook-acquire-Octazen-Solutions http://www.quora.com/Why-did-Facebook-acquire-Octazen-Soluti... http://techcrunch.com/2010/02/19/octazen-what-the-heck-did-facebook-just-buy-exactly-and-why/ http://techcrunch.com/2010/02/19/octazen-what-the-heck-did-f... They were supposedly masters of scraping and contact importing. I would love to know more about this story, but there is not much published about it.