Sorry to hijack OP, but there are strange interpretations of FB's terms of service on here.
Direct quotes from the ToS
"You own all of the content and information you post on Facebook, and you can control how it is shared through your privacy and application settings. In addition:"
Sounds fairly clear to me.
"For content that is covered by intellectual property rights, like photos and videos (IP content), you specifically give us the following permission, subject to your privacy and application settings: you grant us a non-exclusive, transferable, sub-licensable, royalty-free, worldwide license to use any IP content that you post on or in connection with Facebook (IP License). This IP License ends when you delete your IP content or your account unless your content has been shared with others, and they have not deleted it."
The point of this bit is that you are giving them the right to use the pictures on their site. Not in advertising etc, just the ability to make the photos display on their site.
In addition they revoke their right to do this as soon as you delete your photos (unless shared by others).
"When you delete IP content, it is deleted in a manner similar to emptying the recycle bin on a computer. However, you understand that removed content may persist in backup copies for a reasonable period of time (but will not be available to others)."
They have backups because they aren't mad. Anyone with any sense has regular backups of their website, just in case anything were to go wrong with the main server. Obviously once they run the next backup it will have updated to take account of any deletions.
Hope that clears that up.