Hey, everyone. Important note for people running EFI installs of F16: install the 'grub-efi' package manually before you next reboot! A grub update went into updates-testing recently and soon will go stable which splits out the EFI bits of grub into a grub-efi sub-package, but we so far neglected to include a mechanism to make it get installed with a normal yum update. If you have an EFI install you *need* this package installed or your system won't boot. So before you next reboot, make sure you install it manually!
If yum doesn't show the grub-efi package as available it means your mirror doesn't yet have the split-up package, and you're okay for now (because obviously your grub package will still have the EFI bits). But for now, run 'yum install grub-efi' before each reboot just to make sure you don't get stuck.
We're going to update the package so that grub-efi will get installed when you go from the 'old' grub to the 'new split up' grub, which should stop this being an issue later, but right now, be careful!