Installed apps that enable sharing will work with this button; it will open the share experience just like in Windows 8.1 when the Share charm is used. For example – you can select a few photos directly in File Explorer, press the share button, and share directly to Facebook or Twitter if you have these apps installed. This implementation is of course in the very early stages with more work to be done in the coming months! If you have developed a Windows app, you can learn how to utilize the share contract in your app and benefit from this platform capability by clicking here.
Have feedback on this for us? Make sure you are signed up for the Windows Insider Program and use the Windows Feedback app to send feedback directly to us.
(I originally planned to publish this post this week but Brad Sams beat me to it – figure I would go ahead and post anyway.)