Matt Cutts discusses the new Caffeine Sandbox with Michael MacDonald at Search Engine Strategies Show in San Jose. Good stuff to pay attention to, since Cutts suggests that “power users” might notice differences in the rankings between the current default search and Caffeine.
Here’s a suggestion I’d like to make for your testing if you do decide to check it out – play with the “Filter by Date” option in the left rail which appears on the current page if you click “options” on Google’s current results page. For that matter, I’d like to suggest that many of the “options” may find their way into the standard results you get from that new SandBox.
I think they may have already released many of the tweaks in that recently released UI, but found few people using them in that form. So rather than requiring everyone to make choices (or maybe making some of the most “popular” choices already ranked from testing) the Caffeine option may represent choices made based on testing so far.
Now they want to see if you like those choices once they are baked into the default product. That’s my take based on reviews and my own testing. Your mileage may vary and I may be way off base, but it’s a good story.