When I fired up my Surface today I was greeted with 7 updates from the Bing team at Microsoft. The Windows 8.1 updates were for Bing Finance, Bing Sport, Bing Food and Drink, Bing News, Bing Health & Fitness, Bing Travel and Weather.
As is fairly typical of Microsoft app updates there are no details on what has actually changed and there doesn’t seem to be any visible changes so it’s probably all under the hood changes.
Based purely on the pop up that appeared when I ran the Bing News app for the first time after the update it seems to be sync of settings via Sky/OneDrive.