It’s 15th August 2012 & as per the previous announcement Windows 8 is now available for MSDN & TechNet Subscribers.
For Developers, if you have MSDN Subscription then you can download Windows 8 RTM & Visual Studio 2012 RTM.
For Developers here are some of the resources from Visual Studio & Windows Teams.
For IT Professionals, if you have TechNet Subscription then you can download Windows 8 RTM.
Windows 8 Evaluation for Developers
This is intended for developers building Windows 8 apps and IT professionals interested in trying Windows 8 Enterprise on behalf of their organization.
The Windows 8 Enterprise 90-day evaluation is available to developers to build and test Windows 8 apps on the final version of Windows 8. After installing Windows 8, go to the Windows Dev Center developer downloads page to install Visual Studio 2012 and related tools to build Windows 8 apps.
If you’re not an MSDN subscriber, you can download an evaluation version of Windows 8 RTM from TechNet. Note this version will expire and you cannot upgrade.
For details visit http://msdn.microsoft.com/en-us/evalcenter/jj554510.aspx