When you're talking about any business model with IP or sensitive fiscal information but want to embrace social media you need to consider these items.
1. How can I be transparent as possible but not violate/hurt my business? The people who run your social media campaign CAN'T be some lowly intern. If your goal is real relationships and not simply distribution, your social media needs to be owned by you or someone you trust to the end.
2. One of my employees did something that made my business potentially libel. What should I do? This is a tough one and the answer needs to be a contractual one. Employees that own social media need to sign a contract that says, they're libel for essentially "saying something blatantly wrong". The employee needs to be trained on social media best practices AND guidelines about what NOT to do in the name of the company. (Organizations with really good social media departments usually have those individuals build out their personal brands anyway. This is a logical step.
Now . . . that said; I'm not a lawyer nor have a I played one on TV. I'm not sure this is possible but companies are going to have to start thinking about libel and internal personal brands.
3. Can I fire an employee who says something negative about my company online? I worked with someone that lost her job because of a very vague Facebook post. Not sure of the legality but it was not a very professional thing to do. The professional thing would be to talk to the employee and research what is going on. Your business is a niche social network. When a customer posts something negative you address it. Why wouldn't you do the same with the employee? You trusted them enough to hire them. You may find a systemic issue . . .
Like the others who have answered the question. I think the three C's
Confidentiality: I have seen status updates that friends and colleagues have posted that have sent a shiver up my spine.
Criticism: Open criticism of clients, colleagues and the work place. These have been seen appearing on social timelines and they can create a lot of issues.
Content sharing. Not just reports and stuff that are confidential and internal, but also stuff like music, movies etc being shared easily within social networks. A small company could be brought down by one of those RIAA lawsuits.
Client confidentiality - less worried about disclosure than the information security risks and social engineering opportunities that social services offer hackers
IP infringement - the one that keeps me up at night is the indiscriminate use of Google image search to source pictures despite continued education and creative commons alternatives
Consumer Protection From Unfair Trading Act regulation of social media in the UK - covers disclosure of organisational connections, astroturfing, shilling etc
1. Staff on their personal networks accidentally divulging confidential client information
2. Staff on their personal networks criticizing, even libeling, brands and people
3. Protection of internal IP from being shared - e.g. client reports, methodology