A Microsoft document related to Windows 8 has some revealing information.
Apparently the company is prohibiting personal computer makers to allow dual booting on devices that would feature ARM processors and would ship with Windows 8 operating system.
The document states:
MANDATORY: Enable/Disable Secure Boot. On non-ARM systems, it is required to implement the ability to disable Secure Boot via firmware setup. A physically present user must be allowed to disable Secure Boot via firmware setup without possession of Pkpriv. Programmatic disabling of Secure Boot either during Boot Services or after exiting EFI Boot Services MUST NOT be possible. Disabling Secure MUST NOT be possible on ARM systems.
Secure Boot is a security measure to safeguard the sanctity of the machine. But it also prevents the user from running different operating systems on the same hardware. This is something we already see on smartphones where developers have to root/jailbreak their devices to install unauthorized apps and mods. Looks like a similar trend would emerge with the launch of Windows 8 Tablets and Desktops in the future.