From what I can tell by looking at the stylesheet here:
http://www.data.gov/css/nav.css
And google search for part a section of the CSS:
http://www.google.com/search?q=%23header-region+UL.nice-menu+LI{PADDING-BOTTOM%3A0.1em%3BMARGIN%3A0px%3BPADDING-TOP%3A0.1em%3B}&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a
I find the first result to be Drupal.
I couldn’t find the admin section, I’m sure they have disabled all that, or renamed it.
I like what this site is all about!! I like to see some transparency, even if it will never ever be perfect.
