Yes, you can dd the Fedora iso images directly onto USB. They will boot on BIOS, UEFI and even Macs (newer ones work better than old).

I use: dd if=Fedora-18-x86_64-DVD.iso of=/dev/sdd iflag=direct oflag=direct bs=4M

The bs=4M is important, otherwise dd uses 512b blocks which totally kills the throughput to the flash which is erased in blocks.