This page contains links to test images for Secure Boot. The current test image is a Fedora 17 installer using a modified bootloader and kernel, signed with Fedora test keys.
http://pjones.fedorapeople.org/sb/Fedora-17-x86_64-sb4.iso - Fedora 17 Secure Boot test image.
http://pjones.fedorapeople.org/sb/LockDown.efi - key enrollment binary. Execute this from the EFI shell on a system running in setup mode in order to enroll the test keys and transition to user mode.
http://pjones.fedorapeople.org/sb/DB.cer - Binary certificate file containing the public half of the signing key
http://pjones.fedorapeople.org/sb/DB.crt - ASCII certificate file containing the public half of the signing key