While it’s not technically released yet, Unity has flipped the naming scheme of Unity 2017.2 to Unity 2017.2.0f1. The “f” stands for final, so we will probably see a blog post on it soon. This version has a handful of back-end changes, such as improved main-thread performance when issuing commands to graphics APIs, but the visible changes are mostly in two areas: XR (VR + AR) and baked lighting.
From the XR standpoint, a few additions stand out. First, this version now supports Google Tango and Windows Mixed Reality, the latter of which is tied to the Windows 10 Fall Creators Update, so it makes sense that Unity would have support in the version before that gets released (October 17th). In terms of features, the editor now supports emulating a Vive headset, so you can test some VR elements without having a headset. I expect this will mostly be good for those who want to do a bit of development in places where they don’t have access to their headset, although that’s blind speculation from my standpoint.
The other area that got a boost is baked global illumination. Unity started introducing their new Progressive Lightmapping feature in Unity 5.6, and it bakes lighting into the scenes in the background as you work. This update allows you to turn shadows on and off on a per-object basis, and it supports double-sided materials. You cannot have independent lighting calculations for the front and back of a triangle… if you want that, then you will need to give some volume to your models. This is mostly for situations like the edge of a level, so you don’t need to create a second wall facing away from the playable area to block light coming in from outside the playable area.
I’m not sure when the official release is, but it looks like the final, supported build is out now.