Like 99% of similar problems you probably don't have the necessary module(s). I'd like to see the output of "lspci -k" to check if the module was loaded or not. If it was and it's still not working then you may need firmware for it.
Personally just a guess off the top of my head -- I think your wireless card is a Broadcom 43XX chip.
And someone correct me if I'm wrong but I believe Ubuntu ships with networkmanager?