Andrew Gelman also points me to this site, which provides government advice on blogs:
The advice is pretty standard. It does point to some interesting stuff:
CIA, for example, has more than 1,000 internal blogs. See the Federal Computer Week article on the CIA's blogs. http://www.fcw.com/article94152-04-21-06-Web&newsletter=yes
I suppose I should be surprised that this link says the article on CIA blogs is no longer available.