Reposting this from my own "Facebook is down" thread because this one has more visibility:

pi@pi ~ $ curl -I http://facebook.com/

HTTP/1.1 503 No server is available for the request

Server: proxygen

Content-Type: text/html; charset=utf-8

Date: Thu, 19 Jun 2014 07:54:55 GMT Connection: close

Content-Length: 2131