The Broadcom driver was installed by default on my laptop with bcm4311 wifi card during a clean install of Ubuntu (11.10) Oneiric Ocelot, but I couldn't get it to work. Under the wifi icon enable wifi was greyed out, even though bcmwl was activated in additional drivers. Some posts on Ubuntu forums and ask Ubuntu said that the driver had a bug in 11.10. Searching the internet, it gradually became apparent that b43 firmware from Linux wireless is preferred to bcmwl. I removed it from the software center, and it also removed a package called dkms. Then I installed b43 from the software center (but I have used apt-get on my other box to install b43legacy) and rebooted. Viola, wifi.
See http://www.linuxwireless.org/en/users/Drivers/b43#Supported_devices (current) & https://help.ubuntu.com/community/WifiDocs/Driver/bcm43xx (slightly outdated) for more info.