Search Explanations -- Look for the "Explain Search" link on the blue bar of the results page. Choose that after a search and you'll get an explanation of how the search was put together, including how many terms and documents are in the database, how many hits you're getting for each items, and how the search engine is viewing your search.

Keyword-Targeted Advertising -- Now advertisers can advertise on specific keyword result pages instead of general result pages (though it appears that general result pages are still available.)