Microsoft has now published the full changelog to the Windows 10 Mobile released earlier today. Build 10586.164 is going out to those on the Insider Slow and Production Rings.
In addition, Windows 10 Mobile devices like the Lumia 650, Lumia 550, and unlocked Lumia 950 and 950 XL (e.g. non-AT&T) devices are also getting the update.
Full story from the WindowsCentral blog...