Yes, it does. Microsoft call it IRM (Information Rights Management) and you need to install/enable it on your domain and Office 2007 hooks into it.

You can then put limits on who can copy, print, fax the email, who can cut/paste from it, to whom you can forward it and force expiry of it.

It includes fun bits such as "The first time that you try to open an e-mail message that uses restricted permission, you must connect to a licensing server to verify your credentials and to download a use license".

I am sure all the companies who are using it have extremely important documents to mail around ;-)

Or maybe it is all about feeling important...

It can "expire" email after a certain time.