Google’s latest test is apparently to allow users to view a secondary search box in the search results. A search on amazon, for example, would return a search box directly under the phrase but above the URL. Below is an example.
It will also work for a search on wikipedia and even possibly for newspaper news sites as it will for the NY times, which also has Sitelinks.
Upon typing a keyword into the search box and clicking search, essentially you are searching the site via Google’s search engine. So you will be able to view selected areas of another site through Google.
Source: http://searchengineland.com/080304-162923.ph
