While Ubuntu support for ARM hardware is in great shape with Canonical investing significantly in the rapidly-growing ARM-based mobile market and the to-be-growing ARM server-space, plus other Linux distributions taking on ARM, official support for Fedora on ARM hasn't been quick to come by. In fact, Fedora developers still remain unconvinced about taking on ARM as a primary architecture.
For over the past week there's been very long discussions going on within the Fedora development camp about ARM as a primary architecture and then the primary architecture promotion requirements. Some view that there's not enough ARM hardware available, it would take too long to build the Fedora archive under ARM, etc. (There's already been some to specifically point out otherwise with hardware like the Trim-Slice, PandaBoard ES, NVIDIA Tegra 3, and other popular devices.)