Companies need to be diligent with their Social Media policies. It is too easy for employees to post something that can damage the reputation of a company.
It is imperative to create a Social Media Policy that all employees adhere to. There are a number of ways to create this. There are services that can allow you to modify a boiler-plate policy. From there, you can modify it to suite your needs and culture. Another method is to hire an attorney or consultant that specializes in Reputation Management.