It is great to see some big players making concerted efforts for cultivating a collaborative culture that supports their strategy through establishing effective social media policy. Here are a few examples that stand out. Here is Adam Brown, Head Of Social Media at Coca-Cola as interviewed by Andy Sernovitz, author of Word of Mouth Marketing.

IBM-s policy can be seen here: IBM Social Computing Guidelines or heard here: IBM Social Computing Guidelines video
Social Media Governance has created an online database of Social Media policies
Interestingly enough many organizations still have no fixed guidelines or policies on a global scale. These are simple and necessary to improve effectiveness and to avoid major mistakes. The details can come at a market to market level. Kudos to those who recognize this as a top priority. Please feel free to add to the list. I am sure there are many more, although some do not share links to the greater Internet community.