I went to delete my account the other day just because there is so much crap and it's time wasting and I go searching for delete but couldn't find a link! I then came across the deactivate which I had heard about before and went with that but they still keep all my data and it's ready for me just by logging in again.
To delete I had to Google and find an actual link in a forum on how to fully delete my account. And after I found the link you are taken to this page that asks you to confirm and then you have to wait two weeks (I guess to let people go back after Facebook withdrawal.) I guess what I'm getting at is: Facebook makes it easy to deactivate with a false sense to their users that it's sort of being 'deleted.' Yet they are keeping everything, even messages, from your account. I wonder if they still count these accounts in their user count?