Once again, that is a function of the PEOPLE who are using or misusing the site. If someone is an arsehole in real life, that person is going to be an arsehole on Facebook, too. That's not the fault of the program; it's the fault of the person.
Facebook doesn't get a person fired. Posting something stupid on Facebook gets a person fired. The lesson is not, "Don't use Facebook." The lesson is, "Don't be an idiot."
You can't fix stupid!
I don't blame facebook; I don't like it, and I have enough trouble remembering to update my business page (Sad when having that page gives my business credibility!), never mind a personal page. I just don't care enough (Read, "At all) about what other people are doing. I can see the value of it as a communications tool, assuming that for some totally unfathomable reason you needed to communicate with someone else, but as for using it? No thanks. I'll sit and watch apple cores turn brown first.
I don't think facebook either brings people closer together or pushes them apart (in the grand scheme of things), but what it does do is isolate them. Many people replace their whole social life with facebook, and all you have to do is spend a few minutes [trying] to talk to a high-school age child today to realize that conversation and face-to-face socializing are lost arts!