Not only is social networking not private, for the most part you are ceding some, or all, of the rights to material you post to social networking websites. Once your material is on their servers, you’ve essentially given it away. Something to think about.
From the link:
A study conducted by the University of Cambridge discovered that social networking sites such as Facebook and MySpace do not immediately remove from its servers photos that have been deleted by users. The study audited 16 different social networking sites by uploading photos, noting their URLs, and then deleting them. Thirty days later researchers checked the URLs, and in the case of 7 sites, the photos had not been removed from content delivery networks.
The 7 sites are: Bebo, Facebook, hi5, LiveJournal, MySpace, SkyRock, and Xanga.
Other sites were able to remove pictures immediately, and surprisingly, frequent security offender Microsoft was one of them: Windows Live Spaces had immediate removal of photos. Also on the ball were Orkut, Photobucket, and Flickr.