For some times, people who used Atheros chipset for their WLAN devices are confused since it's not integrated in the Linux kernel (yet). They have to use MadWifi drivers who used proprietary HAL to make the devices works on Linux. The pain will be gone in the future.
Few months ago, they (Atheros) had released the ath9k driver for 802.11n ASICs on Linux. It will be part of Linux kernel (hopefully 2.6.27 which will be released in short time) as people have responded and they are pleased to see this driver gets merged in.
Few days ago, they have made another movement by releasing their HAL (hardware abstraction layer) used for their 802.11a/b/g devices under the ISC. This will make the maintenance of the driver gets better in the future and hopefully, better support of all Atheros chipsets under Linux.
Read the announcements on LKML.