I have posted a couple of times comments about the need that organizations must draft a set of rules about the use of social media by employees; incidents of improper (ie. irresponsible, stupid, or abusive) use of social media are countless. Many have lead not only to corporate problems but also have damaged those involved.
With pleasure I found that Coca Cola, one of the companies with official presence in the social media, drafted a set of rules as corporate guidelines for the use of social media by employees. In the introduction the document states that the purpose is "to help empower our associates to participate in this new frontier of marketing and communications, represent our Company, and share the optimistic and positive spirits of our brands". Hopefully more will follow.