I'm not advocating this, by the way.  Do this at your own risk.  But technically-legally-it is kosher to badmouth your business on the Facebook.  You're familiar with the Facebook, aren't you? 

This just in.  According to Inc.com:

In a first-of-its-kind decision, a National Labor Relations Board judge has ruled a New York nonprofit must re-hire five employees who were fired after complaining about their jobs on FacebookAdministrative Law Judge Arthur J. Amchansaid the employees' off-hours griping about their working conditions was protected by theNational Labor Relations Act.

So you CAN do it.  But SHOULD you right now?  In this economy?  Are you feeling THAT secure on your job that you would put yourself in jeopardy just because it's legal?  Remember- you have to be talking to a co-worker in order for you to be covered.

I still say play it conservatively right now.  Just looking out for ya, folks!   Would you do it?  Have you ever done it?  Would love to know.  Don't worry, I won't mention your name!