Once you post something on the Internet, you have lost control of it. Even if you limit the target audience to certain groups, or lists, or whatever Facebook calls it, the information is still free on the Internet. The share/retweet feature has made it easier than ever to copy something someone else said.
I do not put anything on the Internet unless I am comfortable explaining it to someone at some point in the future. I am not making any statements about the value of privacy, or whether web 2.0 social networks like Facebook have any legal/moral/ethical obligation to provide privacy protections.
My point is simply that these lists and privacy settings create a false sense of security. Once you hit the share/post/tweet button, it’s gone. You can’t get it back. And you can’t control where it goes.