PR Machine points to Nancy Flynn’s article on Blog Rules. For the most part it looks reasonable except for this-
To help prevent smoking-gun blog content from triggering a workplace lawsuit, stock slide, or media feeding frenzy, prohibit employees from posting negative opinions or critical comments about the company's people, products, and services.
Part of the credibility of Robert Scoble comes from the fact that he will criticize Microsoft. But obviously you would not want employees making personal criticism of their coworkers.