Ning in the Classroom-Update!

Ok...it's been a week (3 blocks) since I started our Ning project on the 1970's. There was zero content when we started and I encourage you to go and check out the unbelievable amount of content that has been added to the site at www.seventies.ning.com (I believe you have to sign up for Ning to take a look). After introducing Ning to the students on Day 1, I gave them these tasks on Day 2 and Day 3.
I would love to read your comments on this project and the use of a social networking site in the classroom. Many schools have blocked similar sites (myspace, facebook, etc.) and I think this is definitely the wrong direction to take. I did have to remove one video because I thought the content was not suitable for a school project. My biggest concern now is about grading and assessment and determining what they learned about their assigned topic area and other assigned areas. Comments please!