OS News reports Windows 8's new secure boot process may potentially complicate the installation of other operating systems, like previous versions of Windows and Linux:
Microsoft requires OEMs that want to be part of the logo program for Windows 8 to have secure boot enabled. According to Garrett, there are two ways for Microsoft to handle this. "The two alternatives here are for Windows to be signed with a Microsoft key and for the public part of that key to be included with all systems, or alternatively for each OEM to include their own key and sign the pre-installed versions of Windows," Garrett states, "The second approach would make it impossible to run boxed copies of Windows on Windows logo hardware, and also impossible to install new versions of Windows unless your OEM provided a new signed copy. The former seems more likely."
This means Linux, or any other unsigned operating system, will not run on your computer. There are several problems here when it comes to Linux. First, we'd need a non-GPL bootloader (Lilo perhaps?). Second, Garrett indicates that the Linux world is moving towards using the Linux kernel itself as a bootloader. This means kernels will have to be signed, making it virtually impossible to compile your own kernel. Self-signing would still require each key to be included by all OEMs.