Getting the Broadcom Wireless cards to work with gnu/Linux was bit tricky. Even though linux kernel included the free software b43 driver for a long time, getting these wireless cards working needed some manual configuration. In this post I am testing Ubuntu Karmic and b43 driver to configure Broadcom BCM4311 Wifi card. .
$ lspci -vnn | grep 14e4
04:00.0 Network controller : Broadcom Corporation BCM4311 802.11b/g WLAN [14e4:4311] (rev 01)
Subsystem: Broadcom Corporation Device [14e4:0465]
06:00.0 Ethernet controller : Broadcom Corporation NetLink BCM5906M Fast Ethernet PCI Express [14e4:1713] (rev 02)
To get started I used 'Hardware Drivers' to find and load the needed drivers. From main menus select System > Administration > Hardware Driver program or type ' sudo jockey-gtk ' in a terminal. The Hardware Drivers program found two drivers on this machine 'Broadcom B43 wireless Driver' and 'Broadcom STA wireless driver'. I selected the first and then pressed the 'Activate' button. The program connects to the Internet and downloaded the driver, so make sure you have a wired connection setup before hand.
After the driver was setup and rebooting the computer the wireless works perfectly with Network Manager.
Most people use Ubuntu LiveCD to try if their hardware is supported. As of writing this post the Ubuntu LiveCD doesn't configure and load the broadcom drivers automatically.