A Few Gov Blogs actually hosted on .gov domain.
Centers for Disease Control (CDC) Director's Blog
Library of Congress Blog
Pandemic Flu Leadership Blog
Kind of interesting - A NASA Launch Blog
It appears that they just do it during the launch themselves.
NASA's Launch Blog was activated: June 8, 2007 at 1:30 p.m. EDT
NASA's Launch Blog was deactivated: June 8, 2007 at 7:49 p.m. EDT
Rep. Jack Kingston - 1st District of Georgia
Missouri Attorney General's Consumer Blog
Missouri Lottery has a blog, although not hosted on .gov domain address it is an actual state site.
A bit surprised that each Representative and Senator doesn't have a blog setup to share thoughts and insights with constituents, although then it would be in black and white and some would not like that.