Microsoft has confirmed that the final build of Windows 8.1 has been released to manufacturing (RTM), ready for the October 18 release of dozens of Windows 8.1-powered laptops, desktops, and tablets. Historically, the RTM is released to OEMs when the operating system is completely finished -- for Windows 8.1, though, Microsoft has decided to redefine the phrase to mean "it's still buggy and unfinished, but we need to give it to our OEMs otherwise we'll fall behind schedule."