It’s like Mashable knew we were doing a talk on Facebook Groups and Pages for faculty today. This article presents various ways educators deal with interacting with students on Facebook, but unfortunately doesn’t go too much into using Groups or Pages with classes. Even so - it’s a helpful read for inspiring you to solidify your own policy regarding how you interact with students on Facebook.
If you’re an educator looking to start using social media with your students, I also recommend the book Social Media for Educators: Strategies and Best Practices. I went to a workshop given by the author and found her tips and case studies very insightful.