It shouldn't come as a surprise, but it looks like Bing is testing a new search results page that brings a little more Metro to the search engine. Spotted by our forum user, you can see the minute differences versus the current layout.
The image above is of the new results page and the image below is of the current layout.
You can see the difference and if our forum users are anything to judge the layout by, most appear happy with the small update. While not the first to notice the new UI, it does look like the initial rollout/testing started not long ago.
Let us know if you have the updated interface and how it works out for you in real world testing.