Today’s hoopla over changes to the Facebook Terms of Service have prompted a rare blog post from Facebook founder and CEO Mark Zuckerberg. In the post, Zuckerberg falls short of apologizing for the changes, but rather, uses the opportunity to explain why Facebook more or less keeps your content indefinitely.

He writes, “When a person shares information on Facebook, they first need to grant Facebook a license to use that information so that we can show it to the other people they’ve asked us to share it with. Without this license, we couldn’t help people share that information.” This is true – without making this part of the Terms of Service, someone could technically claim they didn’t know anyone would see their Status Updates, as silly as that may sound.

Continuing, Zuckerberg explains why the site keeps content indefinitely. “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.”

That makes sense as well, but I don’t think it gets to the heart of the issue that has people so concerned about Facebook’s terms of service, as the company fails to answer the question of why this piece of the TOS was removed: “You may remove your User Content from the Site at any time. If you choose to remove your User Content, the license granted above will automatically expire, however you acknowledge that the Company may retain archived copies of your User Content.”

Ultimately, Facebook’s stance can be summarized as “trust us, we won’t do anything bad.” Zuckerberg writes, “In reality, we wouldn’t share your information in a way you wouldn’t want. The trust you place in us as a safe place to share information is the most important part of what makes Facebook work.”

In the end, this fiasco isn’t going to change the way I use Facebook, and I imagine it won’t do much to alter other user’s plans either. Their terms of service, like those of any other company operating on the Web, are designed to put their interests first, and eliminate just about any potential legal risk that their lawyers can think up.

Once again though - like with Beacon and the Facebook re-design revolt - Facebook has done a poor job of communicating the changes, leaving Zuckerberg on the defense instead of proactively keeping users informed on potentially controversial moves the company is making.

Chances are Facebook won’t abuse the privileges they are granted under their TOS. The backlash over doing something insane like using member photos without permission would be enormous and Facebook is smart enough not to do it. But as a user, it’s another reminder that what you do on the Internet is probably permanent, and much of it, probably outside your control.