Windows 8 certified systems will make it either more difficult or impossible to install alternative operating systems.

M$ is compulsory requiring EFI Secure Boot feature to be enabled, which will prevent competing operating systems to be booted. Disabling this restriction, pardon "feature", will be optional and at the discretion of Firmware manufacturers and OEM (such as Lenovo, HP, Dell, etc.). The extra money and/or benefits M$ will provide OEM in case they abide with its requirements will certainly push these companies to maximize their revenues instead of caring of the 0.1% or less users of Linux.

Read more on this on the Matthew Garret (RedHat) blog: http://mjg59.dreamwidth.org/5850.html