I don't know if this will still interest anybody, but I found a lot of confusing stuff on the www about installing the Broadcom STA wireless driver in ubuntu lucid and had to figure it out myself. This method should work (Tested with 32bit and 64bit on Apple iMac 7.1 and MacBook Pro 5.1):
Update your system.
Install the backported kernel: 2.6.35-28-generic (2.6.35-25-generic in 64bit). Also works with 2.6.35-28-generic-pae.
Boot from it. If you use the nvidia driver and get low graphics mode, choose "run in low graphics mode for one session", reinstall the nvidia driver and reboot. For the ATI driver see this thread: http://www.linuxquestions.org/questi...-fglrx-865082/
Remove the 2.6.32 and older kernels and headers (You want the initramfs updated for 2.6.35, not 2.6.32; if you want an emergency fallback kernel, install 2.6.31-11-rt. No kidding; the rt-kernel is still in the repository and will boot into recovery mode when the newer kernels won't).
Download and install the natty kernel source from Launchpad (https://launchpad.net/ubuntu/natty/+source/bcmwl
bcmwl-kernel-source_126.96.36.199+bdcom-0ubuntu2_i386.deb or bcmwl-kernel-source_188.8.131.52+bdcom-0ubuntu2_amd64.deb, according. (Read the terminal output of the installer: it should do update-initramfs for 2.6.35).
Reboot, and on the next boot you should get a "wireless networks available" message.
In terminal geek talk it goes like this:
sudo apt-get update && sudo apt-get dist-upgrade
sudo apt-get install linux-image-generic-lts-backport-maverick linux-headers-generic-lts-backport-maverick
# be sure to reboot into the new kernel!!!!
# purge old kernels:
sudo apt-get purge linux-image-2.6.32-31-generic linux-headers-2.6.32-31-generic
sudo apt-get purge linux-image-2.6.32-30-generic linux-headers-2.6.32-30-generic
# repeat the purge commands for any older kernels except 2.6.31-11-rt
#sudo apt-get install nvidia-current
#for the ATI driver see this thread:
# for 32bit:
sudo dpkg -i $HOME/bcmwl-kernel-source_184.108.40.206*
Edit: If you have another account on your computer and it gives you display trouble after upgrading the ATI driver, do the following:
sudo cp -R $HOME/.gconf $HOME/.gconfd $HOME/.gnome2 $HOME/.config $HOME/.dmrc /home/<user>
sudo chown -R <user>:<user> /home/<user>/.gconf /home/<user>/.gconfd /home/<user>/.gnome2 /home/<user>/.config /home/<user>/.dmrc
whereby <user> is to be replaced with the short name of your secondary account. You will have to do some cleaning up after this, but the display should work again.