At first I thought I wouldn't be too interested in nings, because I'm not really into the social networking phenomenon. I have kind of viewed it as something for people with too much time on their hands who have a burning desire to reconnect with people with whom they attended high school.
When I read 7 Things You Need to Know About Nings, I was very impressed with the example from a college class where students had to create networks around specific political issues central to an upcoming election. I had not considered using social networking in this way. This is something I could see adapting to an educational setting. You could set up a book club network, for example, with each group in your classroom or school responsible for keeping up a group within the network. Students could be required to post a certain number of times, to answer certain questions, to add certain resources, etc. I have a 4th grade teacher I am planning to share this idea with next week.
I looked at the librarian networks, but did not find much that interested me as an elementary school librarian (a problem I have noticed in many aspects of Web 2.0 technologies- a focus on older students). I poked around on Ning a bit more, though, and found a group called ReadKiddoRead. It has a lot that interests me, and I joined. I love the linked lesson plans for various books, and there were lots of suggestions to encourage reading. I'm looking forward to seeing how I can integrate this into my library.
So, in summary, I am a bit more sold on the whole social networking thing than I was, and look forward to delving into it a bit deeper. Still don't think I'll be setting up a Facebook account, though.