Quoting MarioninTurkey:

In the "old days" employers used to have huge phone bills. Now with msn chat etc people can at least spend a few minutes sorting out their private lives / checking their kids got home from school OK / making a doctors appointment etc etc without costing an employer more.

As an employer and a manager myself, I can say that the majority of staff work hard and are dedicated. These guys can come in a few minutes late with an emergency, do a bit of facebook, go home half an hour early because the gas man is coming, and it is no problem because when we have a rush on and they need to stay late to finish the work, they do so. It is give and take. I treat them like an adult and they behave like one.

Other staff members (the very small minority) sadly don't deserve any trust, they mess around at any opportunity, are always the last in and first out. The best thing is not to check up on them, but get rid of them! In actual fact, normally it isn't me (the boss) that gets wound up about them first, but their colleagues (peers) who feel they are not taking their fair share of the workload!