# Notice: if you would like to crawl Facebook you can
# contact us here: http://www.facebook.com/apps/site_scraping_tos.php
# to apply for white listing. Our general terms are available
# at http://www.facebook.com/apps/site_scraping_tos_terms.php
(Then there's a bunch of "Disallow:" statements for Baidu, Google, etc.)
If you follow the link, you can apply to Facebook for permission to do "automated data collection." Even if you do get permission, Facebook is very restrictive with what you're allowed to do with the scraped data.