Facebook has taken a step in the right direction by adding the ability to add a link to your public PGP key.  It also allows you to see which of your friends have keys.  Hopefully it will also spread the word about PGP and allow for a more secure/safer social networking site.  Granted, with PGP, there is a level of trust needed.  However, it is still a step in the right direction and affords the benefit of no need to go searching public key servers looking for the key you need.  You can find the app located here www.facebook.com/apps/application.php