Today the U.S. Marines renewed its ban on the use of social media in its ranks. The distraction is one thing, but the security concerns are quite another, and the Marines feel Twitter, Facebook and other social media are a haven for those who would undermine the effectiveness of the troops. Not surprising in that context.
A little more surprising was the order by the ESPN sports network that its employees not Tweet unless "it serves ESPN." Presumably that means only Tweeting about programming or the advancement of its journalism, but at this point it's early to presume.
The surprise in this case is in the context of other organizations that have established guidelines for employees, ostensibly permitting them to participate but reminding them not to embarrass themselves or their outlets through their activities. There are significant brands to protect and reputations to uphold, and many have opted for policies to do so, but they bear in mind the advantages that come with public conversations and the generation of new audiences for content. Sudden edicts outlawing activity aren't common in this regard, so it will be interesting to see how ESPN explains its approach.