Earlier quoted context omitted.
As a site owner you can pay Google for this: https://www.google.com/work/search/products/gss.html I used it several years ago to power this site search: http://www.poetryfoundation.org/search/articles#qs=ginsberg It works pretty well (disclaimer: I'm not sure this is still being used on that site)
Yes. It's been around for years. I have used it but this misses my point or proves it. Either way, sites need to figure out how to power own search.
Since we had all the data the results from Google were compared to a local search I setup in Sphinx (http://sphinxsearch.com/) and the Google results were more relevant and it was a lot cheaper to deploy.