I asked this question on Quora a few days ago: http://www.quora.com/Facebook-1/Why-is-the-new-Facebook-Add-a-Location-to-Your-Photos-feature-so-good-at-guessing

I asked this question on Quora a few days ago: http://www.quora.com/Facebook-1/Why-is-the-new-Facebook-Add-a-Location-to-Your-Photos-feature-so-good-at-guessing-the-location http://www.quora.com/Facebook-1/Why-is-the-new-Facebook-Add-... but did not get any responses.