Using Twitter and Facebook

You may have noticed in the today@trinity announcement that the graduation office is using Twitter and Facebook to communicate with upcoming grads. I wonder if this will be a growing trend for announcements on campus? And I wonder if students will get annoyed if they get too many announcements that way? Maybe if they volunteered to sign up for it, like in this case, they would be okay with it. I wonder how many would voluntarily sign up for library announcements? Probably some dedicated library users.