Late last month Microsoft announced that Windows 8.1 had reached the RTM phase, that particular build was leaked soon after that. The company initially didn't allow developers to download the final copy of Windows 8.1 before its October 18th official release date. In a blog post today, the company says that it has heard complaints from MSDN and TechNet subscribers and has decided to make the copy available to them from today. Apart from making the Windows 8.1 Core and Windows 8.1 Pro edition available today on MSDN and TechNet, Microsoft has also released a Visual Studio 2013 RC build for developers.
Ubergizmo , Windows 8.1 Released For MSDN And TechNet Subscribers, Windows 8.1 Released For MSDN And TechNet Subscribers