We are working on this issue now and there is an interesting article by Indian and Grieve (When Facebook is easier than face-to-face: Social support derived from Facebook in socially anxious individuals - available through Google Scholar link) that touches on it. Several other studies that are coming out. It is an interesting issue and one that people are trying to study but it is tricky. You might also look at work by Yalda Uhls from UCLA on the impact of taking away technology on ability to recognize others' emotions.
Thanks for the great question!
LR