Here's a long list of various government and private sector social media policies in the US. Many of the links are broken, but with a little Google sleuthing, I'm sure they can be found if there's a particularly interesting policy (huh - I never expected to use "interesting" and "policy" side-by-side...).
http://govsocmed.pbworks.com/w...d%20Best%20Practices
Are you allowing all (or many) staff to engage under the official banner of MYM or TVFS? Or are they using their personal accounts to engage? Or is all messaging going out through the communication department? We've talked about all of there scenarios at the Mental Health Commission, and there are (obviously) pros and cons of all three approaches.