No-one ever deletes things. When you "delete" your account, for example, they aren't going to invalidate their last set of backups. They aren't also going to anonymize all the comments/messages you sent that now reside in other people's profiles. Any information you give to any social networking site belongs only partially to you, partially to them, and partially to the members of your network with whom you have interacted.
This appears to have been recently added. Of course, this being Facebook, there is no certainty they actually remove all your data.
I should note this is different from the "deactivate" option which simply disables the account.
