Rubén Gómez reports that Microsoft is testing removing the underlines on the hyperlinks within the search results in Bing.
The Bing search results still have the blue hyperlink look, but the underline was removed in this Bing test. Bing is constantly testing large and small changes like this to see how searchers interact with the change and if it leads to a higher click through rate and a happier searcher.
Here is a picture of a typical Bing search results set with underlined links:
Here is a picture of Bing testing removing the underlines:
Google has also recently gone from underlined hyperlinks to removing the underlined hyperlinks in the search results. Right now, Bing is just testing making the change.