Is your boss an unholy jackass of a man (or woman)? Do you really just want to vent your vitriol somewhere, someway? If so, I would highly recommend you avoid doing it on any of your social media accounts. Doing so could get you fired, and you may not have the courts to help you out. Free speech may not come into play in these situations, and that is bad news for workers.
In light of a decision by the National Labor Relations Board in a case involving Walmart, people are being told to be very wary of saying negative things about your company and/or boss on social networks. These problems are becoming more and more complex, in large part because of how social networks straddle the public and private fence. It is also unclear, from this decision, what rights and protections, if any, workers do have.
As far as the company is concerned, a post by a disgruntled employee can cause real damage to the business. What’s more, if the company is publicly traded, this information could run afoul of SEC restrictions on insider trading. As ridiculous as this all sounds, a simple tweet could land a person in hot water. What needs to happen is a worker’s bill of rights. People need to know what is expected of them. It’s only fair, after all.
I would say that you are going to have much happier and productive employees if they have a place to vent. Another way to alleviate the issue is to have more open and honest communication at the company. Then you negate the need for the negativity elsewhere. Nonetheless, I do not see this changing anytime soon. It would be entirely too simple to come up with a solution. They gray works better for those in power.