Here are some good tips on how not to get fired for blogging...
I haven't had a problem yet. My stratagy has been to promote my blog all of the time at work. This insures that everyone is annoyed enough with me that they will never read it. ;-)
Actually I am careful with what I say, I just ran a seach for my employer's name and it doesn't return any entries. I ran a search for 'boss', and I only find one entry, and it is generic, and applies to my behavior, not theirs.
Business is such a fun topic to discuss, it is a bummer that it can be so dangerous. I would guess that there is a little bit of 'Dilbert' or 'Office Space' in every workplace. It is a bummer that many companies don't have a sense of humor about it.