Yes, I already have a couple of Raspberry Pi, but I had to get one of the new Raspberry Pi 2 (model B), to check out its increased processing power with OpenCV and image processing.
So, lets install it. The Arch Linux install page is here. This new RPi2 has a new ARMv7l Cortex-A7 quad-core! Arch Linux has a new distro page dedicated to it. If you want to install the previous RPi model you can also follow my notes, you just have to get the correct SD image here.