My dell laptop with a Broadcom BCM4311 wireless card refused to connect to wi-fi. Ubuntu 11.10 prompts to install the drivers but installs the incorrect drivers. Instructions elsewhere on the web also mentioned to install the driver but didn’t mention the exact driver. I ended up spending several hours troubleshooting the wifi but finally these instructions solved the issue. Hope they work for you as well.
$ lspci -vvnn | grep 14e4
09:00.0 Ethernet controller : Broadcom Corporation NetXtreme BCM5752 Gigabit Ethernet PCI Express [14e4:1600] (rev 02)
0c:00.0 Network controller : Broadcom Corporation BCM4311 802.11a/b/g [14e4:4312] (rev 01)
Remove the incorrect driver & install correct one:
$ sudo apt-get install firmware-b43-installer
$ sudo apt-get remove bcmwl-kernel-source