Google has long distributed its search engine on third-party content sites. But until today you could only search the individual site or the Web -- and the branding on search results was practically all Google. Now Google will allow site owners to customize its search index and the look and feel of the results. Think industrial-strength Rollyo, with a twist of Swicki.
Google is releasing Google Custom Search Engine, which enables publishers to set up site search together with a limited index of sites (domains or sub-domains) that they specify, up to as many as 500,000 sites I was told. Google's Custom Search is "free," but comes with AdSense alongside search results. That requirement is exempted for governments, non-profits and educational institutions. Perhaps the most basic and obvious aspect of this is that it potentially creates more AdSense inventory for Google.
But what is perhaps most interesting about the new Custom Search is that publishers (large or small) can allow anyone or selected colleagues, friends or community members to contribute to that index. For example, if I own a site dedicated to stamp collecting and have a group of regular contributors or trusted readers I can allow those individuals to contribute their selections to this index. This gives the index the ability to evolve and grow over time -- and makes it "social."
Seen in a different way this is Google doing an interesting version of "social search." Google is distributing its engine and giving potentially thousands of human editors the ability to slice and dice its index in myriad specialized ways, creating vertical and sub-vertical search results. (All results are not new crawls of the included sites but rather slices of the larger Google index crawl.)
Political or ideological groups can use this to offer only those results that affirm their world views or screen out those that contradict it. And there will certainly be some of those uses. But equally sites could develop niche indexes that are more vertically rich than general Web search, drawing upon the specialized knowledge of their communities.
This project is largely under the umbrella of Google Co-op, which was launched with considerable fanfare earlier this year but confused many people. The project was intended as a way to be help Google offer deeper and more vertically authoritative results in different content categories, and a way to enable experts and publishers to contribute their content to Google search results -- if users subscribed to those "feeds."
Google hasn't formally indicated any specific plans regarding how it might or might not tap the collective wisdom of these Custom Search Engines. It's my guess that Google will find ways to leverage all the work that these publishers and human editors will do with the product to make its own search results better.
Postscript from Chris: I've got more on the new service, including instructions for building your own custom search, in today's SearchDay article, Google Launches Custom Search Engine Service.