Originally Posted by wige

The display of the simplified site map (I keep forgetting what it is actually called) is completely algorithmic. The requirement for that to be displayed is that based on the user's query, the search engine knows that the first domain is far more authoritative than any of the other pages in the listings (often happens when searching for a company name, or the name of a concert or sports venue) and the search engine is unable to determine based on the query what section of the site the user is looking for - no one page is authoritative for the query relative to other pages on the domain, even though the domain itself overall is authoritative.