Microsoft Bing has added some subtle effects to the search tools bar filters where you can filter the search results by news, images, videos, etc. When you hover your mouse over the options, Bing might color the background of each option or might use a monochrome color.
Here is what it looks like, this was sent to me by Frank Sandtmann, but I was and am able to replicate this as well:
It is cute to see Microsoft Bing testing all these minor things…
Forum discussion at Twitter.