Dubbed Google Caffeine, a variety of changes were made.
While doing a vanity search this morning, I noticed that not only 'freshness' (last update) is displayed in the main index search results .... but a right click on your mouse drops down more information.
In this case, 'Get more results from the past 24 hours'.
Talk about speed ? Wow!
Update: The right click functionality seems to have 'turned off' in the past hour ... however the index is still running at an incredible speed. Will the feature come back? We'll see :)