Reading the man page for bwi on FreeBSD 8.0, it says it supports "Broadcom BCM43xx IEEE 802.11b/g wireless network driver"
Quote:
To compile this driver into the kernel, place the following lines in your
kernel configuration file:
device bwi
device wlan
device wlan_amrr
device firmware
Alternatively, to load the driver as a module at boot time, place the
following line in loader.conf(5):
if_bwi_load="YES"