Hi!
I've committed the AR9287 support to -HEAD. It'll be there for 9.0-RELEASE.
No, I don't have any plans to backport the code to 8-STABLE; but I know that the code compiles and works on -8. You can just checkout sys/dev/ath, sys/modules/ath, sys/modules/ath_pci, build ath/ath_pci modules and enjoy the updated support.
I don't read these forums often, so if there are any other atheros related chipset support questions, please point out the relevant forum thread to me directly.
Thanks!