Under Facebook’s current terms (which can change at anytime), by posting your pictures and videos, you grant Facebook “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.” Beware of the words “transferable, sub-licensable, royalty-free, worldwide license.” This means that Facebook can license your content to others for free without obtaining any other approval from you! You should be aware that once your photos or videos are shared on Facebook, it could be impossible to delete them from Facebook, even if you delete the content or cancel your account (the content still remains on Facebook servers and they can keep backups)! So, although you may be able to withdraw your consent to the use of photos on Facebook, you should also keep in mind that if you share your photos and videos with Facebook applications, those applications may have their own terms and conditions of how they use your creation! You should read the fine print to make sure you are not agreeing to something that you don’t want to have happen.
Twitter’s photo sharing service, Twitpic, just updated their terms of Service on May 10, 2011 (which, of course, can and will be updated at any time, from time to time). By uploading content using Twitpic, you are giving “Twitpic permission to use or distribute your content on Twitpic.com or affiliated sites.” You are also granting “Twitpic a worldwide, non-exclusive, royalty-free, sublicenseable and transferable license to use, reproduce, distribute, prepare derivative works of, display, and perform the Content in connection with the Service and Twitpic’s (and its successors’ and affiliates’) business, including without limitation for promoting and redistributing part or all of the Service (and derivative works thereof) in any media formats and through any media channels.”