This guide only works on i386 platforms, so if you're running an x64 linux, then you've to try again with ndiswrapper or wait for a new solution from atheros and madwifi.
1. Open you terminal
2. Get this version of madwifi:
wget -c http://snapshots.madwifi.org/special/madwifi-ng-r2756+ar5007.tar.gz
3. Untar the downloaded package:
tar xvf madwifi-ng-r2756+ar5007.tar.gz
4. Get inside the unpacked directory:
5. If you haven't compiled anything from source before on your linux then you propably need the build essential package:
sudo apt-get update && sudo aptitude install build-essential
6. Now you can build your madwifi and install the modules:
sudo make install
sudo modprobe ath_pci
sudo modprobe wlan_scan_sta
The last 2 commands can cause some complications on some systems. If they do check your System >> Administration >> Restricted Drivers Manager and disable atheros here. Then try again.
7. Now restart your computer and you should be able to see any aviable networks in your Network Manager.