Upgrading my wife’s laptop I found out that Ubuntu Karmic Koala comes with Linux kernel version 2.6.30 which does not have linux-restricted-modules anymore. Instead you have to install DKMS (Dynamic Kernel Module Support) package to build required modules on demand. Below is how I solved problem with Broadcom Wifi card driver on the laptop:
$ sudo apt-get remove linux-restricted-modules
$ sudo apt-get install build-essential dkms bcmwl-kernel-source
$ sudo reboot
Don’t forget to load newly compiled module after rebooting.
$ sudo modprobe wl
After that NetworkManager recognized the WiFi card and connected home WLAN in a blaze.