With the R1 kernel ath5k/ath9k are broken, but thats not because of drivers.
It is due to iw (iw - Linux Wireless)

Backtrack currently uses an old version from here
Index of /download/iw/

The bt repo should be updated with the git version of iw
git clone git://git.sipsolutions.net/iw.git
this fixes nl80211 for monitor