Think of what happens in the most effective classroom learning environments. In the midst of scholarly work in the classroom, students and teachers often times discuss personal events and happenings. They talk about what they did over the weekend/holiday, share very personal stories, discuss personal tragedies, share pictures, etc. A huge component of teaching is building really good relationships with kids-and part of this process involves getting to know them on a personal level.
Why do we view the online world any differently? In the midst of really effective learning that can go in in spaces like Facebook, ning, Twitter, skype, wikis and other highly social-collaborative software tools, teachers and students engage in both scholarly problem solving and personal relationship building.
I don't think it is any more difficult to maintain boundaries in the online world in comparison to the physical world for the teacher-student relationship. I actually think it is easier in the online world because the conversations are more transparent and open for others to see. When I comment on a student's facebook post, his/her parent is able to see my comment...I consider that a good thing!
You mention that using software to connect and collaborate causes un-easiness amongst parents and administrators...why would this cause any more uneasiness than a teacher taking a group of students on an over night field trip, retreat, or simply engaging in scholarly activity in the classroom?
I would strongly encourage teachers not to be friends with their students on facebook. Facebook is a social networking site but it is personal not educational. Teachers should draw line between work and personal life. There are plenty of means for teachers and students to contact each other, and I do not think facebook should be one of them.
I think that regardless of the content of your social life it is inappropriate for students to become to involved in it. I work mainly in higher education and private tutoring so the lines are little blurry but I think that the distinction must be maintained for there to be teacher/student relationship. At the same time I think it's now absolutely necessary that a practicing educator have an online presence and be accessible through the tech medium. It's a tough area to wade through and there are many solutions. Personally, I maintain an educator page on Facebook that is publicly visible (My personal page is private and no students are ever added, despite the fact that there is nothing inappropriate there) and I police the content on a regular basis. Additionally I maintain a twitter account specifically for communicating with students and/or colleagues and education based social networking. I'm still adjusting exactly how I interact with the people I teach and work with online, it's likely that it will be a continuous process my entire career. Good food for thought.