I may be too early with this question but here goes - I would like to do a clean install of Windows 8.1, and I have a product key for Windows 8 Pro (the boxed "upgrade" they sell retail).
The RTM bits released on MSDN and Technet and such are designed to be installed standalone but they require a key that is specific to the 8.1 bits. You can't plug in a Windows 8 key and have it work.
The RTM bits released on MSDN and Technet also refuse to allow you to install without a key so the idea of trying to plug in the Windows 8 key after the fact isn't possible, and the ei.cfg things that would work with Windows 7 don't seem to apply anymore.
It could be that a really obvious way to do this will become apparent in October but if I wanted to do a clean install of Windows 8.1 with a Windows 8 Pro key, is that possible?