I don't think there is another X driver ready yet. But at least two are in development. One requires quite some patches to the kernel with dma and stuff and is not released completely yet and another one tries to use glamor.

1: http://www.raspberrypi.org/phpBB3/viewtopic.php?t=4649
2: https://github.com/Factoid/xf86-video-rpi

I don't think the glamor one would work on archlinux arm since it uses X.org 1.13 and as far as I know glamor doesn't work on 1.13 yet.