Facebook friends are not really friends. There is a huge level of distrust in the community when you can't speak your mind for fear of being fired or tagged in compromising photos.
These are not real concerns I have when I'm among real friends.
One of my colleagues has a very strict rule that he does not become friends with current work colleagues on Facebook or any other social network. Seems like a good idea to me, although there is sometimes a blurry line when you work with some of your good friends. I'm sure having such a rule makes him less concerned about the compromising photos or status postings.
It's odd that Facebook hasn't allowed users to turn off all tagging to the Wall. You can turn off friends posting links to your wall, but not photos. Bad incentivizing.
These are not real concerns I have when I'm among real friends.