As a response to growing Bing and Facebook search engines, Google is developing next generation search engine with new architecture. It keeps the features and internals secret.
The development version is available at http://www2.sandbox.google.com/. The only difference I found when I googled “Next generation Google search engine” is search result. Current engine gives 37,300,000 results, and the new one gives 10,100,000 results (could be more accuracy!).
Differences between these has been explained at http://www.betanews.com/article/Googles-next-search-engine-Whats-the-difference/1250012846.