Google Launches "Search Within a Site" Function

Google is always adding more functionality to its Google Search facility and a couple of days back it announced on its Google Blog that it had 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.

This provides searchers with potentially better results and is a step further than the "Sitelinks" which often appears for more trafficked sites. The examples that I have seen on the web have primarily been for large US, business, military and government sites. The example below shows that even "local sites" already have this search within a site element:

This now means that with many websites you no longer need to use the command