I ran into a small problem last night. I tried to update my packages using Shaman, the rather excellent package management for Arch Linux, but it complained when trying to upgrade pacman.
It turns out that Shaman does not support the latest version pf pacman. So for now at least you will have to remove (pacman -R) Shaman and use pacman direct from the command line to manage your packages.
Or you might use one of the other package managers and if you do I would be interested to hear which one and why you use it.