Basically I have a website. I have a properly setup sitemap so I assume Google knows about all of my pages. And I've seen on some sites, the search form leads to a page with the shell of the original site but the results are clearly provided by Google. Similar to codinghorror.com's search, however his results aren't shown within his website's layout.
Any idea what I'm talking about or how to achieve this?
^ Perhaps you're looking for Google Custom Search Engine