So this is what happened. Microsoft finished work on the final RTM version of Windows 8.1 but held off releasing the build, much to the charging of the IT community, on MSDN and TechNet.
Redmond claimed that RTM in this case was not Release to Manufacturing, but instead Release to Manufacturers — as the company wanted to give hardware vendors enough time to customize and put the operating system on the devices they are readying.
But while the world was waiting to get their hands on Windows 8.1 RTM earlier than the official release date of the OS, the operating system was leaked onto the web.
So even though the technology titan initially planned to launch Windows 8.1 for everyone in October, it had a change of heart yesterday whereby it published the official RTM version on its developer channels, MSDN and TechNet in order to give developers time to prepare their apps for launch.
While many users are already running Windows 8.1 RTM, there were some doubts about the authenticity of the leaked 32-bit and 64-bit configurations.
Now it appears that the leaked builds that were released in late August are basically identical to the ones Microsoft published yesterday. Hash checks confirmed that these versions came from Microsoft.
This is actually the main reason why activation of the new operating system is possible with a legitimate Windows 8 key. So if you are running a leaked build it might well be safe.
And those of you without MSDN or TechNet subscriptions, Windows 8.1 will be available as an upgrade to the Windows Store on October 17 for Windows 8 users, and October 18 for everyone else.