Preview users on Windows 10 Mobile can download a new version of the Microsoft Photos app from the Windows Phone store. Unfortunately, this appears to be a minor release, with no immediately noticeable additions or improvements.
The updated app has the version number of 15.902.19222. If you do notice any new changes or additions in Microsoft Photo, please let us know about them in the comments.
At this time, the desktop version of the app is stalled at 15.827.16340. We'll update the article if that changes or we find anything new.
Thanks to Aakash for the tip!