The University of
Minnesota uses Twitter and Facebook in English lessons as a matter of
course, as part of its Digital Media programme.
This short video gives a little more information about it.
It would be interesting to know if this programme has led to increased grades -- the video basically says it should, but doesn't actually say it has.
I think it's useful to know that there are officially-sanctioned classrooms, underpinned by academic authority, that use these modern communications applications as part and parcel of their work. I wonder if there are similar programmes going on in the UK?