As a librarian and professor, I joined Facebook last year when I found out that the students in my public speaking class were communicating with each other via that tool, instead of our university's email system. It was amazing how much more open and willing the students were to sharing information about each other and their individual and group projects in our class, via Facebook. They were thrilled that I was willing to join Facebook, and they loved that I used it to find out and celebrate their birthdays, for instance, as they came up during the semester.
I read this and got inspired. So I grabbed an account at facebook via Dominican and found one of my students. I added her. We'll see how this goes.