Google has made available for developer preview a new search infrastructure--"next-generation architecture for Google's web search". Google is soliciting comments and feedback on how search results compare to the old structure.
Potentially speed has been improved in this new search model. Relevancy may have also improved in the search functionality as well as size of the Google archive--which in turn will drive more relevant ads.
The URL for the sandbox is: https://www2.sandbox.google.com/