Lots of congrats go to websites that get their sub categories linked as authorities on the G engine, but what if your directory got it's search box included as an "authority" search? I've never seen this before. Any directories out there that have this kind of results?
Apart from that site ive only seen it for some of the huge sites like flickr, quite cool though if you have that showing in the results though. Ive never seen a directory with that yet.
Sub-links has absolutely no weight towards authority. However the search feature is offered by Google, I believe it is called business search. If you have this service you get the search box below your designated url.
I am not saying authority as in SERP, but more of a visual affect... but here is a quote from G's blog... Through experimentation, we found that presenting users with a search box as part of the result increases their likelihood of finding the exact page they are looking for. So over the past few days we have been testing, and today we have fully rolled out, a search box that appears within some of the search results themselves. This feature will now occur when we detect a high probability that a user wants more refined search results within a specific site. Like the rest of our snippets, the sites that display the site search box are chosen algorithmically based on metrics that measure how useful the search box is to users. http://googleblog.blogspot.com/2008/03/search-within-site-tale-of.html