Small note, following a discussion I had in -devel, I greatly doubt that FF 2.0 will make it into FC6 -updates - too much trouble involved.
Most likely it'll wait till FC7.
If you -really- want it (Or if you're using KDE - in such a case, breaking epiphany doesn't really matter...), just download the SRPMs and build them - it should work just fine.
DEV: Intel S2600C0, 2xE52658V2, 32GB, 4x2TB, GTX780, F20/x86_64, Dell U2711.
SRV: Intel S5520SC, 2xX5680, 36GB, 4x2TB, GTX550, F20/x86_64, Dell U2412..
BACK: Tyan Tempest i5400XT, 2xE5335, 8GB, 3x1.5TB, 9800GTX, F20/x86-64.
LAP: ASUS N56VJ, i7-3630QM, 16GB, 1TB, 635M, F20/x86_64.