This bit deals with making wireless works in Ubuntu 7.0.4. I meant this to be a reference for myself (in case I run into the same problem again), so I apologise for the lack of generality. =)
Broadcom Corporation BCM4306 802.11b/g Wireless LAN Controller
sudo apt-get install bcm43xx-fwcutter
This is basically to install the guy that will extract the relevant firmware from the driver =)
Something to note: during installation it may report a problem that a certain file could not be found etc etc (I forgot the actual problem) Just ignore it. =)
Step 2: Download the driver file wl_apsta.o.
The catch here is there are many versions of wl_apsta.o floating around out there. I tried a few versions before I managed to find the correct one (and I am sure to back it up!) Assuming you have got the correct version, let's move on.
Step 3: Run the firmware cutter on wl_apsta.o
sudo bcm43xx-fwcutter -w /lib/firmware wl_apsta.o
/lib/firmware is basically a place to store all the firmware files (there will be A LOT) extracted.
Last Step: There will be NO need to reboot your machine after this step. If everything goes well, you will be able to see your wireless connectivity bars up and running (I am assuming you have set up your wireless correctly, meaning it is working in MS Windows) :P
If, for some reason it is not working, I highly suggest you try another copy of wl_apsta.o. Delete the firmware files from /lib/firmware/ and repeat the extraction.
A good way would be to compare the md5 of various wl_apsta.o files to differentiate them and try different ones until you get it up =)