@rgomezric spotted a new Bing user interface test, where they moved the navigation bar below the search box.
Bing is testing three different flavors of this test and @rgomezric captured all of them.
Here is the current interface followed by the three tests (you can click to enlarge all of them):
Bing is testing, always testing just like Google and Yahoo. In fact, Yahoo is currently testing a card like design interface for their search results.
Bing is also testing a new image search interface, as he noted. Here is a video:
Forum discussion at Twitter.