If I take the F17 Beta RC4 x86-64 desktop live and write it to USB with dd, it shows up as EFI bootable. However, if I try to boot it via EFI, this doesn't totally work. It makes it to grub and shows me the grub graphical menu as it should. However, when proceeding (whether by hitting enter or waiting for the timeout), it stays showing the graphical grub screen with no text for a while, with a cursor appearing and disappearing a couple of times. It then finally displays the usual 'allocating foobar for vmlinuz' or something like that message - but after a much longer delay than you usually see when booting EFI from a USB stick - and then, a few seconds later, simply reboots the system. I've tried several times and with two different USB sticks and this is reliably reproducible on my hardware at least. I checked the sha256sum of the image and it was good. Booting the same stick via BIOS emulation works, but installation to hard disk fails: I'm filing a separate bug for that.
I also see this with RC4 netinst.iso so it isn't limited to live. I get a black screen and no text right before the reboot. I'm fairly sure this must be a kernel problem. I have also seen it when using a custom boot.iso with only the EFI partition added, not the MAC EFI partition so that isn't the cause. The same iso written to usb with livecd-iso-to-disk boots just fine on EFI so this has to be related to booting from a hybridiso usb stick.
grub-efi-0.97-89.fc17.x86_64 fixes this for me. I built a test boot.iso dd'd it to a USB stick and successfully booted it on EFI and Mac EFI.
TC2 Live-Desktop ISO dd'd to a USB stick is bootable on Mac EFI, however verification fails when choosing Verify and Boot Fedora from the GRUB menu (2nd option). User is inadequately informed of the failure. For dual boot installation on Apple hardware, the bug results in Bug 817262: File system errors left uncorrected, failure to install along side Mac OS.
Confirmed fixed as of TC3. The other issues Chris reports are not related to this bug. -- Fedora Bugzappers volunteer triage team https://fedoraproject.org/wiki/BugZappers