Everyone seems to be focusing on the .gov site but if you take a look at the Stack Overflow home page, the page that would normally get indexed highly, there is very little telling Google what it is.<p>There is no <meta name="description"> tag in the header. The H1 tag, important to Google, says "Top Questions". The content of the first page constantly changes.<p>Plus, I would bet that most of the links into Stack Overflow are to individual articles, not the home page. Any particular article probably doesn't outrank a popular .gov site.<p>This is just very poor SEO on Stack Overflow's part.