"HowTo.gov" is a new website from the US General Services Administration for government staff on how to communicate online with Web Content, Social Media, Contact Centers (call centers), and Technical Solutions (Cloud computing, mobiles, apps...). This is similar to the guidance which the Austrlaian Government Information Management Office provides on topics such as Web Publishing.
The problem with such guidelines is the breadth and complexity of what government does. I have used the Australian Government guidelines for teaching web design. I suspect that policy agencies would be better off providing systems and training which has the policy embedded in it. That is rather than giving a complex explanation of what must be in a government web site, provide an interactive service where government staff can enter details and have the web site created.