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.)
Bringing on ARM support within Fedora was brought up during Monday's FESCO (Fedora Engineering & Steering Committee). It was another long discussion; the meeting logs are available. They decided to establish a sub-committee to investigate the requirements for formal promotion of different architectures to be considered a primary architecture or secondary architecture. ARM may end up being a secondary architecture, which would be similar to being a "PA" (primary architecture) but with a different Koji build status and ARM bugs would not be considered release blockers for Fedora.
There is though unofficial Fedora ARM builds already for recent releases, among other Fedora ARM initiatives, which are all documented on this Fedora Project architectures Wiki page.