Just booted up the new Ubuntu Karmic release in live mode prior to the installation. I always do this to check if there are any incompatibilities with hardware on a new release. This has happened a few times in the past due to driver and kernel module changes.
I checked the live mode to make sure the initial plug and play installed all the drivers needed for the basic operations. The hardware drivers assistant detected the BC4312 wireless card and offered either the free or the proprietary drivers.
If you have worked with Ubuntu in the past, you may have noticed that the free drivers for the BC43 chipsets are very buggy and often lack WPA connectivity so you will have to stick with the proprietary drivers to begin with and replace them later on.
So I rebooted and installed Karmic Koala on my HP550.
After the installation process the hardware driver assitant listed neither the free driver nor the proprietary one which can get you stuck if you are depending on a wireless connection.
In order to get the drivers running, you will have to install the b43-fwcutter package via
apt-get install b43-fwcutter
After the installation, the hardware driver should be listed (if this is not the case, simply reboot the machine).
Select the Broadcom 802.11 Linux STA wireless driver and reboot the machine and you are good to go.
There still needs to be some more improvement handling hardware drivers in Ubuntu to make it more accessible for beginners, but overall the plug & play regarding hardware has become very decent – in my experience even better than Windows 7 if you are not using the newest hardware.
Btw. 9.10 has gone official