Not the one for digging old threads up,
However spending a good amount of time finding a wireless usb card for backtrack with monitor and injection modes. I stumbled upon a old(ish) b/g/n usb card in the back of the cables draw.
Small inconspicious Belkin F6D4050 v1 monitor/inject. Chipset is a RAlink RT2870/3070
Finding anything that works on both OSX 10.8 and backtrack with mon/packetinject is a complete ball ache so might be of use. Relatively easy to pick up in the UK unlike the alfa cards.
Also running a Mbp on 10.8.2, so it has been tested on both backtrack and osx ml.
Backtrack - runs out the box.
Mac - driver from Belkin site.