The Fedora distribution is often associated with laptops and desktops using x86 processors. These systems are cheap, powerful, and readily available to developers, and so it would naturally follow that they would be well supported. But Fedora has long supported systems based upon architectures other than the venerable x86.
Such systems include those using PowerPC (and its bigger cousin, POWER), SPARC, and even mainframe processors. Collectively, these alternatives are known in the Fedora nomenclature as secondary architectures, and they have historically tended to target more niche users (the number of readers owning a mainframe is likely small).
What makes the ARM port different than many of the existing Fedora secondary architectures is that ARM-based hardware is, like x86, cheap, readily available to developers, and is increasingly becoming more powerful. It has not yet reached the level of a high-end x86 desktop or laptop, but decent performance can be had from an embedded board or netbook system costing under $200. The latest systems use dual core ARM Cortex-A9MP processors such as the OMAP4 from Texas Instruments, or the Tegra2 from Nvidia, with more-capable processors on the horizon. Each of these systems feature around 1GB of RAM, a decent amount of storage options, and good network connectivity, along with a host of peripheral devices.