In 2009, Facebook made a bold grab to own everyone's content, forever. This is the text they put in their terms of service:
You hereby grant Facebook an irrevocable, perpetual, non-exclusive, transferable, fully paid, worldwide license (with the right to sublicense) to use, copy, publish, stream, store, retain, publicly perform or display, transmit, scan, reformat, modify, edit, frame, translate, excerpt, adapt, create derivative works and distribute (through multiple tiers), any user content you post on or in connection with the Facebook Service or the promotion thereof subject only to your privacy settings or enable a user to post.
Fortunately, they've since backtracked and weakened the language considerably. Here's the relevant section today:
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: 1. 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 content that you post on or in connection with Facebook. This license ends when you delete your content or your account unless your content has been shared with others, and they have not deleted it.