Microsoft and Facebook announced this morning the availability of the new Windows 10 Facebook app. While the app is not a true UWP as it uses Facebook's own Osmeta developer tool it does have many new features and that familiar Windows 10 design.
Version 4.0.0.104.191 is now live in the Store, and it re-uses the link for the original Facebook app for Windows 8.1
Full story from the WindowsCentral blog...