Google Recently started showing authority listing for some sites for search phrases either for their business name or keywords relevant to that category. Recently Nate Whitehill posted that his blog gained an authority listing. There are several factors which determine for Google to list your site as an authority. Till now nothing is clear about it, some evidence that links and relevant content could be the factor to be deemed as an authoritative.
If you are running a sitemap and have a Google webmasters account you can see weather you site has gain authority listing. Under Google Webmaster Tools on the right navigation you can see a link called links under that category you can see Site Links.
Some of my evidence shows the following factors determine a authority listing.
1) You domain name or business name used in link pointing to your website. Also the same term being using inside the content of the web pages.
2) The Domain name is been used as an anchor text while linking.
3) You Domain name or Business name has links from local directories and sites like Better Business Bureau.
4) The term people searches and the destination pages has a strong relevancy.
5) A search Query which has been searched for several times to reach that destination.
6) Link from higher Page rank web pages.
The bottom-line is relevancy and links of your web pages and anchor text of your business.