Define Your Governance Plan
By the time you're considering deploying the social computing features of SharePoint, you should already have a well-documented governance plan. The most important general governance policy for community features is never allowing users to post anonymous content. One reason for "flame wars" on the public Internet is the fact that people can hide behind pseudonyms and post anonymously. Inside the organization, a general best practice is to ensure that all users "own" their comments and content. This helps to ensure that everyone plays by the rules and makes it very easy to ensure that governance policies are followed.
Even if contributions are allowed to be anonymous in some circumstances, it's almost always possible that at least the system administrator will be able to see who posts what content. With a documented policy and user names associated with content, this barrier becomes much less of a real risk.
Your governance plan will also need to include specific guidance for at least these community features: My Sites, ratings and tags, blogs, and wikis. You will likely already have some policies that apply to social computing, such as privacy rules and appropriate use of computer resources. You may need to update these policies to reflect your social computing deployment.
For some of your employees, the use of social computing features will be completely new. Especially for these users, it's important to include guidance and examples of effective use of social computing features in your governance plan, and you should provide training to help make the governance plan "real." For example, for people who are confused about what makes an effective status update, you might suggest that they use status posts to "narrate" their workposting at the completion of a major deliverable or work product, or posting questions when they're stuck on something.