I'm also on the "Big Three" - Facebook, LinkedIn and Twitter.
I also don't like the idea of job-related stuff on Facebook. While I am Facebook friends with many of my former co-workers (I just started a new job last week), and also have some of them as connections on LinkedIn, I never mix the two. On LinkedIn, I'm all business, and that's the way it should be. I don't post anything about the goings-on at anyplace I may have worked, aside from generalities that everyone can relate to (and things that are in the news anyway). However, I can be somewhat outspoken on some issues (if you are a FB friend of mine, or follow me on Twitter, you know what I'm talking about). I respect other people's opinions, however, and I would not un-friend someone just because we differ on some issue.
Anything I post to Twitter gets posted to my Facebook timeline as well (but not retweets).
There are some people that post borderline disparaging remarks about there employers on Facebook, however, and that makes me cringe. Don't get me wrong; I'm all for freedom of speech. But remember that just because you can
say something in a public forum, doesn't mean you should
There are laws to protect the freedom of the press's speech, but none that are worth anything to protect the people from the press.