Today, Microsoft has released the Windows 8 RTM and Windows Server 2012 R2 RTM bits for MSDN/TechNet Subscribers. As rumoured earlier final build version is 6.3.9600.16384.
If you are an MSDN/TechNet Subscriber you can download the latest build from:
Related blogs for reference:
Download Windows 8.1 RTM, Visual Studio 2013 RC and Windows Server 2012 R2 RTM Today by Steve “Guggs” Guggenheimer’s blog