Google is constantly testing user interfaces, we cover some but not all of them. This one was brought to my attention by AbhisheK Kasaudhan on Twitter.
This tests gives you a whiter, what looks to be more spacious, desktop search experience.
The top bar is less gray and more off-white, it is also more spacious. The search button is not a blue button but rather a white button with a blue magnifying glass. Here are the two interfaces side by side, you can click to enlarge them.
Whiter Test Interface:
The Normal Interface:
Which do you like better?
Forum discussion at Twitter.