Here is the official changelog from Major Nelson:
Earlier this month, we added a host of new features and improvements on Xbox One and starting today, members of the Xbox One preview program will get to check out even more new features – some of which are planned for the March system update.
Check out the list of features in the March preview update that are starting to roll out tonight:
Screenshots – While playing a game, you can now take screenshots on your Xbox One console by simply double-tapping the Xbox button on your controller to capture a screenshot and pressing Y to save the screenshot. If your Xbox One is equipped with a Kinect, you can also say “Xbox Take a Screenshot” to take and save a screenshot.
Upload App – The Upload app is being updated so that you can manage your screenshots in addition to your game clips. You can use a screenshot as your background, by viewing the screenshot in full-screen mode from the Upload app, then, press the Menu button and select Set as background.
Suggested friends – With the suggested friends feature, the Friends area in home and your friends list will help you find and add friends. Suggested friends will include people you might know, so you add more friends to game with, and top community broadcasters and clip creators, so you can get more great content in your activity feed.
Sharing your name – We’re rolling out two new ways to share your real name; with all of your friends or to everyone in the Xbox Live community. You can also continue to share your real name with select friends, or with no one, if that’s what you prefer. Gamertags are still the primary method of identifying yourself on Xbox Live, but sharing your real name helps people recognize you who might not know you by your gamertag.
Tile transparency – We continue to listen to your feedback and are adding a setting to enable you to vary the level of transparency for your background images. Go to Settings ->My Xbox -> Tile transparency.
Privacy & online safety settings – We added a new setting for sharing voice search data to create an option for users to allow collection and analysis of voice data when they use Xbox – Bing to search.
Report spam – The Messages app has an added option to allow you to notify Xbox when you receive spam. You can now select a specific message, press the A button and then select Report -> Spam to report a specific message as spam.
OneGuide for Australia – Support for OneGuide will continue in preview in Australia for free-to-air TV listings.
Xbox One Digital TV Tuner in Australia – Xbox One owners in Australia with an Xbox Digital TV Tuner can now use it with the preview builds of this month’s release.
Let us know what you think of this month’s preview and stay tuned for more news on Xbox One system updates. And remember, the most effective place for your ideas, suggestions, and feedback to be seen by the teams that create Xbox products and services is at the Xbox feedback site.” Major Nelson