Using Facebook in the Classroom?

Has anyone tried this yet? I teach 5th grade so I probably will never attempt it and I never thought it was a good idea until I read an article on the website emergingedtech.com. This article is told from a high schooler's perspective. The student was reflecting on how he liked that his teacher used facebook as a reader's response log. The students would join the group and then post their responses to the reading on facebook. My first thought was that the teacher could use blackboard or moodle in the same way so why use facebook. This was also brought up in the article and the student felt that students were more engaged because they love being on facebook anyway and they already know how to use it so well! Since it was a group created for the class there was a "wall" between this class and the social aspect of facebook. I liked this article last night, because I was just thinking that someone should create a facebook for schools so teachers can use it in their classrooms. I think that kids would love it.