As some of us have learned the hard way at one time or another, you need to be a bit careful what you say online. Social Media tools like Facebook and Twitter take this to a whole new level. Read this example from a guy who is supposed to be an expert on Social Media.
I want my kids to read things like this so they can be aware of what potential employers will be able to learn about them. In the past, kids could be kids and noone really knew what they had done. But with the Internet doubling as a never-ending archive of conversations, etc., these sorts of things never just go away. You need to make sure that you and your employees are aware of all this too.