in a professional business environment most companies use and control ms exchange.
you can filter out all sorts of nonsense as well as major control of each node.
kerio firewall also has a great vpn access for those roaming salespeople.
we use msn at one place i do freelance stuff in, at another place each computer is equiped with a camera, the boss can see if your sitting in your seat basically, and emails are the only way to communicate so there is a digital record of what happened.
you cant just rock up to the water stand anymore and check progress, most larger firms need it all to be recorded digitally.