Bing is running another test in their search results which highlights what they view as important links – such as Login, Contact Us & Menu pages.  They appear to the right of the site links for the organic search listing, with a shaded box surrounding each one.

When you click on the page, it takes you directly to that page on the site.  Many of them are duplicated, which leads me to believe that perhaps they are testing if the box design is a better way to display sitelinks to users.  In this case, the Menu and the Locations links featured in both the boxes and the sitelinks go to the same page.

Here is another example of Alaska Airlines.  Again, the check in, flight status and book a flight boxes all go to the same pages featured in the sitelink.s

How Bing is choosing these pages is unknown, but it is likely based somewhat page popularity, so perhaps they are tracking the most-visited pages of these sites and then highlighting them.

They aren’t appearing for everyone, as they weren’t appearing in all browsers for me.