Comment 17 for bug 224498

The source code is released and merged into kernel 2.6.27:
http://madwifi.org/wiki/news/20080929/hal-source-code-released

Try and see if it works. Blacklist the non-free drivers in /etc/modprobe.d/madwifi and unblacklist ath5k, then reboot.
It's under development, but in the near future I'll expect it to work out of the box. Ath5k for Atheros AR2524 worked for me in 2.6.27-4 but is broken again under 2.6.27-7. Dmesg actually says it's under development.

If the ath5k (or ath9k) doesn't work, then use the latest hal( remember to unblacklist it):

wget http://snapshots.madwifi.org/madwifi-hal-0.10.5.6-current.tar.gz
tar -xzvf madwifi-hal-0.10.5.6-current.tar.gz
cd madwifi-hal-0.10.5.6-current
make
sudo make install
reboot