Keep it separate....
Surely it can't be hard? I never, ever, ever mention work on Facebook, not even "nearly home time" - similarly, I don't have anyone from work as a "Friend" on Facebook, no matter how well I get on with them.
I do this for the same reasons I don't sit at work and discuss the minutia of my home life - because my home life doesn't affect my work life and (slightly harder) vice-versa - I keep as much distance between the two as possible.
If you want to sit there and say "My Boss, Mr Edwards is a complete tosser & I stirred his tea with my winky" and that goes out so that "Mr Edwards" can be identified then don't be surprised when it gets back to him & you're in his office on Monday. Likewise, if you have the name of your firm on your profile, and you slate them online - don't be surprised to get a rollocking.
In fact, it's precisely because of things like this that most firms now have a "Social Media Policy" and if you're in breach of it you haven't got a leg to stand on.
Sure there's a right to free speech, but there's also a right to not be stupid.