Comment 15 for bug 711397

It seems the right solution depends on your card. If I understand correctly, my BCM4306 rev 2 card is not supported by the bcmwl driver, so the solution above is not relevant for me even if it works for many others.

If I were to guess at the problem, the firmware-b43legacy-installer is fooled by a component of the output of lspci:
lspci -vvnn | grep 14e4
02:03.0 Network controller [0280]: Broadcom Corporation BCM4306 802.11b/g Wireless LAN Controller [14e4:4320] (rev 02)

I think the 14e4:4320 makes b43legacy-installer convinced this is a BCM4320 card, which is b43 and not b43legacy. Hence it refuses to install. However, this page:
http://linuxwireless.org/en/users/Drivers/b43
suggests that this output is expected and that one really is supposed to use the b43legacy firmware.

After first ensuring that b43-fwcutter was installed, I followed the "manual" instructions later on that page:
export FIRMWARE_INSTALL_DIR="/lib/firmware"
wget http://downloads.openwrt.org/sources/wl_apsta-3.130.20.0.o
sudo b43-fwcutter -w "$FIRMWARE_INSTALL_DIR" wl_apsta-3.130.20.0.o

After a reboot, I had to manually start the driver:
sudo modprobe b43legacy

But then it seems to work (it finds and connects to my network). I will insert "b43legacy" into /etc/modules to get this to happen automatically at boot.