I managed - some time ago last November/December - to boot ArchLinuxARM on Radxa Rock (Engineering sample) and even managed to load KDE (albeit without Mali support).
The process was quite confusing: I flashed an own-compiled kernel (3.0.36+) based on Linux3188 (I used the source from Galland's git) to the recovery partition and prepared a rootfs which was written on a microSD card (you can get the RR-ready ArchLinuxARM rootfs from here
). I just followed a simple tutorial here
on creating the rootfs for your favourite distro.
Since then there is a ton new stuff on Radxa and even Mali400 acceleration is available
for Xorg, preliminary u-Boot support plus a 3.10 kernel complete with devicetree support; I will try - when time permits - to update my rootfs to include all new developments but I really hope that ArchLinuxARM team provide an official install package soon.