I work at an inn so blocking the wireless at work would be silly and we'd get so many complaints if our guests could not get facebook. No one would stay in our hotel! Also, I'd be bored out of my witts end during the slow periods at night when I work when no one is around to talk to. Sometimes I feel like the late night security guard who has to be there just in case there is a crisis.
If it's during a time when I need to constantly check in people, then I don't even look at facebook.