As per the last few comments in https://bugzilla.redhat.com/show_bug.cgi?id=799401 , John Ellson and myself both saw 'SYSFONT=True' in our grub configurations after upgrading to F20 via fedup (he from F19, I from F18). Not sure exactly what's doing this, but dracut seems like a good first guess. All my entries in grub2.cfg contained the string, and so did /etc/default/grub .
d'oh - kparal suggested that this just happened because I hit the old bug when I first installed this machine, and never fixed it. I just checked, and he's dead right: Sep 9 21:54:52 vaioz kernel: [ 0.000000] Command line: BOOT_IMAGE=/vmlinuz-3.10.9-100.fc18.x86_64 root=/dev/mapper/luks-04f0d645-1640-4a77-b2bb-769bb28a4de4 ro rd.lvm=0 rd.dm=0 rd.md.uuid=9fedcf34:eb34c8d5:6fab593b:db7424a6 KEYTABLE=us rd.md.uuid=8b2620e2:dbde0283:7af9f824:0ce381cc rd.luks.uuid=luks-04f0d645-1640-4a77-b2bb-769bb28a4de4 SYSFONT=True LANG=en_US.UTF-8 rhgb quiet so I actually had the bad entries in my grub config back in F18, before I ever upgraded. Closing. *** This bug has been marked as a duplicate of bug 799401 ***