There's some storm in a teacup around Facebook's terms of service which is in reality just another iteration of the freak-out-because-web-company-changed-their-terms-of-service that we see in the blogosphere every couple of months. For the most part this is a boring dance but there is an interesting issue around end user expectation around sharing content and ownership of their personal data underneath all the melodrama.
The point of interest is called out in Mark Zuckerburg's post On Facebook, People Own and Control Their Information where he writes
One of the questions about our new terms of use is whether Facebook can use this information forever. When a person shares something like a message with a friend, two copies of that information are created—one in the person's sent messages box and the other in their friend's inbox. Even if the person deactivates their account, their friend still has a copy of that message. We think this is the right way for Facebook to work, and it is consistent with how other services like email work. One of the reasons we updated our terms was to make this more clear.
The issue of what to do with content a user has shared when they decide to delete the content or attempt to revoke it is in an interesting policy issue for sites geared around people sharing content. When I've discussed this with peers in the industry I've heard two schools of thought. The first is that when you share something on the Web, it is out there forever and you have to deal with it. Once you post a blog post, it is indexed by search engines and polled by RSS readers and is then available in their caches even if you delete it. If you send an inappropriate email to your friends, you can't un-send it. This mirrors the real world where if I tell you a secret but it turns out you are a jerk I can't un-tell you the secret.
The other school of thought is that technology does actually give you the power to un-tell your secrets especially if various parties cooperate. There are ways to remove your content from search engine indexes. There are specifications that dictate how to mark an item as deleted from an RSS/Atom feed. If your workplace uses Outlook+Exchange you can actually recall an email message. And so on. In the case of Facebook, since the entire system is closed it is actually possible for them to respect a user's wishes and delete all of the content they've shared on the site including removing sent messages from people's inboxes.
I used to be a member of the second school of thought but I've finally switched over to agreeing that once you've shared something it's out there. The problem with the second school of thought is that it is disrespectful of the person(s) you've shared the content with. Looking back at the Outlook email recall feature, it actually doesn't delete a mail if the person has already read it. This is probably for technical reasons but it also has the side effect of not deleting a message from someone's inbox that they have read and filed away. After all, the person already knows what you don't want them to find out and Outlook has respected an important boundary by not allowing a sender to arbitrarily delete content from a recipient's inbox with no recourse on the part of the recipient. This is especially true when you consider that allowing the sender to have such power over recipients still does not address resharing (e.g. the person forwarding along your inappropriate mail, printing it or saving it to disk).
At the end of the day, many people would like to use technology to solve what is essentially a social problem instead of adjusting their behavior. The bottom line is that even though it is technically possible for Facebook to delete my private messages from your inbox when I decide to delete my account, it would be harmful to your user experience AND it doesn't buy me anything since you've already seen the content. The real solution is for me not to have sent any messages to you that I'll later regret in the first place.
Now Playing: Bush - Everything Zen