Update: The Lumia 950 (XL), Lumia 550 and the LG Lancet are now supported. Furthermore the Windows Device Recovery Tool supports these four phones now.
All Windows 10 Mobile Insiders can press the update button on their phones because Microsoft has just published the new Build 10586.29. As expected the build only brings bug fixes and security updates. It is the first cumulative update for Windows 10 Mobile and is available for both members of the slow and fast ring.
The update brings support for four new devices. The Lumia 950 (XL), Lumia 550 and the LG Lancet will be available to Windows Insiders early next week.
There will be an article about the new build and my experiences in the next days.