Suzanne Lucas, who blogs as Evil HR Lady, isn't really evil, she's just uncomfortably candid about many workplace truths that her fellow HR professionals tend to gloss over.
One of those truths is that in general no one owes you tenure in your job, even if you do it well. In our society, the principle of employment at will is still (fortunately) given much legal weight, meaning that an employment relationship continues only if both sides want it to.
And a consequence of that might just be that the law creates no right to slag your employer on your Facebook page one evening and demand that your employer overlook it the next morning:
So, why am I in favor of companies being able to terminate an employee for online behavior? (These things, of course, aren’t limited to Facebook. Myspace, Twitter, and blogs are all good candidates for firing). Here are 3 Reasons.
Easy firing=easy hiring. I want companies to hire people. In fact, my fondest wish is that all my readers who are searching for jobs find one this year. The more restrictions government places on terminating employees, the more hesitant companies are to hire new people.
Bad judgment isn’t limited to online behavior. Companies need employees they can trust to make good decisions. If you lack the critical thinking skills to say, “Hmmm, if I post that my boss is a jerk, my boss just might find out about it,” then you probably lack the critical thinking skills to do your job. Yes, people vent. But the internet is not private. And anyone who thinks they can trust all their 476 friends to keep something quiet isn’t someone I want on my staff.
Companies should be able to presume loyalty. I know, I know, your company doesn’t care much about your career and they have no problem firing you, so why should you care about them? Because they pay you to care about them....
You can read the whole thing, including the rest of her reasoning, here.