Bing is testing a new search results design - the design makes for a fresher and cleaner feel, without removing any of the features from the current design.
There are several larger changes:
(1) The logo is yellow in the new design, changed from gray.
(2) The search button is yellow, instead of gray.
(3) The black top bar turned white in the new design
(4) The sidebar is white, not gray, in the new design
Here is a video of the new design:
Forum discussion at Twitter.