The whole search results screen does a barrel roll, literally.
The tilt one has been around for a bit, but the do a barrel roll seems new.
Google told Search Engine Land:
Today’s fun query, 'do a barrel roll', was created by a Google software engineer with the primary goal of entertaining users - while showcasing the power of CSS3, a presentation feature of modern browsers. The 'do a barrel roll' query, which causes the search page to spin, will remain in place for a while.
Plus, it only works on modern browsers.
Here is a video: