From the Facebook FAQ
If you deactivate your account, your profile and all information associated with it are immediately made inaccessible to other Facebook users. What this means is that you effectively disappear from the Facebook service. However, we do save your profile information (friends, photos, interests, etc.), so if you want to reactivate at some point, your account will look just the way it did when you deactivated. Many users deactivate their accounts for temporary reasons and expect their information to be there when they return to the service.
If you permanently delete your account, all personally identifiable information associated with your account will be purged from our database. This includes information like your name, email address, mailing address, and IM screen name. Copies of some material (photos, notes, etc.) may remain in our servers for technical reasons, but this material is disassociated from any personal identifiers and completely inaccessible to other users. Facebook also does not use content associated with accounts that have been deactivated or deleted.
Why they keep photos and notes for technical reasons would be beyond me. Maybe they don't have the means or are just too lazy to remove that. Like I said I never did the photo/note stuff. Was just looking for old friends from school.