The Lumia 950, and its larger sibling, the Lumia 950XL, have just received a software update, taking them from Windows 10 Mobile build 10586.0 to build 10586.29. This is a minor update to fix some bugs and improve some upgrade scenarios (and it's the update that will form the basis of our review of the operating system) but the content of the update itself is not really the important bit.
What's remarkable about the update is two things. First, that it exists and is apparently being rolled out by Microsoft, at Microsoft's discretion, on Microsoft's timeline. Second, and related, that this update has a corresponding update for Windows 10 on the PC: Microsoft's mobile and desktop systems are aligned. Windows 10 receives an update on Patch Tuesday and so Windows 10 Mobile receives an update on Patch Tuesday.
Windows 10 Mobile build 102586.29 was distributed to members of the Windows Insider program late last week, and opened up to Insiders using the 950 and 950XL, including AT&T units, yesterday. That much is unexceptional. The Windows Insider program, and before it, the Developer Preview program have for a few years now enabled Microsoft to push out new builds of Windows Phone 8.1 and Windows 10 Mobile to any Windows device, even if it's carrier-branded and carrier-locked.