If you block all of Facebook, add the following to your host file. I recommend pointing them to 169.28.5.13.
127.0.0.1 www.facebook.com
127.0.0.1 facebook.com
127.0.0.1 static.ak.fbcdn.net
127.0.0.1 www.static.ak.fbcdn.net
127.0.0.1 login.facebook.com
127.0.0.1 www.login.facebook.com
127.0.0.1 www.sv-se.facebook.com
127.0.0.1 sv-se.facebook.com
127.0.0.1 fbcdn.net
127.0.0.1 www.fbcdn.net
127.0.0.1 fbcdn.com
127.0.0.1 www.fbcdn.com
127.0.0.1 static.ak.connect.facebook.com
127.0.0.1 www.static.ak.connect.facebook.com