[bootload]

"... It's fairly easy to deactivate or delete your account. Account > Account Settings > Deactivate Account. ..."

Is all the data deleted? cf: Eben Moglen ‘Freedom in the Cloud’~ http://www.isoc-ny.org/?p=1338

[houseabsolute]

I think they actually make an attempt to do so when you delete (not deactivate) your account. However, this goes beyond the promises they make to you in their Terms of Service and beyond, in my opinion, any moral duty they have to their users.

[bootload]

"... I think they actually make an attempt to do so when you delete (not deactivate) your account. ..."

Facebook has repeatedly removed services [0] that allowed you to remove all traces of your account via the API ~ http://www.google.com/search?q=facebook+suicide

[0] Cnet, Rafe Needleman, "Facebook cuts off Suicide Machine access" http://news.cnet.com/8301-19882_3-10424683-250.html