Interest in, even compulsion to use Facebook can be turned into a positive where there is focus and purpose, being in touch with those with whom you want a relationship, not social, but social - like, in most cases you do better business and you develop a sense of trust or at least common purpose.
There are 43,000 members of the OU student Facebook site.
They are there to decide on courses, share as we do in forums their trials and tribulations while being offered ideas and tips, as well as seeking advice. It requires monitoring and moderation, like a good host you act as a catalyst (if required). A great deal is self-generated. There is learning as you'd find in any group or individuals sharing ideas. But can it be formalised? (would you want to run a class during break or recess?) And what happens if students shift to Google+ or others, or do you provide your own social learning network within a 'walled garden.'
For close friends they may have a separate account, or use different networks such as Tumblr.