Great post by Ryan Bretag and a conversation that needs to occur. Great questions posed, like; Should Teachers Accept Friend Requests From Students", and "Should Teachers Request Friendship From Students". I think there are many benefits to online learning and social interaction. I agree with what Ryan says and maybe a Ning is a much tighter and private space for these learnings to be modeled and applied. I use wikis for that purpose because I'm in a K-6 setting and because I want to model safety first. I think that there would be a lot of professors that would be very appreciative if the students came into their classes with strong digital safety education and experience in these settings.
That said, I tweet and I don't mind if my students read along...I keep it clean and try to respect those boundaries we need to have.
Here's a post that also covers this topic pretty well. Thanks Ryan for asking the questions!