Well then I'm definitely doing something wrong. I'd really like to know what it is, as I've been fighting for a few months now.
On my most recent install, I followed the basic procedure on here:
http://blogs.arm.com/software-enablemen ... hromebook/
I used this rootfs:
http://os.archlinuxarm.org/os/omap/Arch ... tfs.tar.gz
I ignored the ALSA and touchpad stuff and initially installed the kernel from ChromeOS beta channel. I then booted to Arch, uninstalled linux-omap and linux-headers-omap, did a pacman -Syu (using a USB ethernet adapter), and installed linux-chromebook, linux-headers-chromebook, and crda. I then rebooted back to ChromeOS and installed the Arch kernel to the SD card. Reboot back to Arch and try the wireless with wpa_supplicant and it fails.
How does that differ from what you did?