Here's an excerpt from the very first link I posted under this topic.....It's VERY "concerning".....
Ace in the hole
These incidents demonstrate that as blogs and social networks like Facebook, LinkedIn, and MySpace become more popular, you need to develop a game plan for dealing with these new forums and technologies.
Some employers have developed policies regarding blogging. Many blog policies call for a prohibition of blogging at work and ask employees to make it clear that they are writing about their own views and are not representing the company when they post messages online. Policies also require employees to keep all identifying company logos and marks off their blog sites.
While you can regulate most aspects of blogging or electronic communication, you can't regulate Internet discussions about topics protected by the National Labor Relations Act, which means you can't prohibit or regulate employees from discussing wages, hours, or working conditions. You also have to be careful about disciplining employees for blog content that may be protected under various whistleblower laws, and public employers have to watch out for speech that could be protected under the First Amendment.