Getting the Broadcom BCM4318 [Airforce One 54g] working under Ubuntu Natty only relies on getting the proper wireless firmware installed. Kudos to NMI who did the in-depth testing on this one.
In Synaptic package manager, install the firmware-b43-installer package. Or, at a terminal, enter the following:
sudo apt-get install firmware-b43-installer
This should install the necessary firmware and enable your wireless device within moments.
It sounds like this may be related to the BCM4328 chipset issue.
Please share any feedback you have in the comments below. Thank you.