I've checked the Ubuntu 10.04 beta2 LiveCD and there it is the same procedure as above, but step 3 must be:
3. sudo modprobe -r b43 ssb wl
because the b43 uses sbb, therefore b43 must be removed earlier.
Better is the clean shutdown in beta2, this works as expected and very quick.
Maybe the final release 10.04 will automatic support the WLAN Broadcom BCM4322, but it don't looks so, therefore the above procedure is the one which works.