Intel has published their Social Media Guidelines.
I like their approach of giving users guidelines for they should and should not do. The context is to place the responsibility on the individual. It is that person who is creating the content. They are responsible for the content and the consequences. I think it is a great balance of encouraging people to interact with responsible behavior.
Intel could have added some specific recommendations for some high profile sites. Of course the sites are changing so often that it might be hard to keep the policy up-to-date.
I also like how Intel integrate these guidelines with other policies like the Intel Code of Conduct (.pdf) and the Intel Privacy Policy. This modularity avoids duplication and inconsitencies.