I upgraded to 10.04 and have the same problem. This is on my work machine which is a 24" iMac.
lo no wireless extensions.
eth0 no wireless extensions.
pan0 no wireless extensions.
sudo ifconfig wlan0 up
wlan0: ERROR while getting interface flags: No such device
dmesg | grep wlan0
lspci | grep Network
04:00.0 Network controller: Broadcom Corporation BCM4322 802.11a/b/g/n Wireless LAN Controller (rev 01)
lsmod | grep b43
b43 174953 0
mac80211 238128 1 b43
cfg80211 148386 2 b43,mac80211
led_class 3732 2 b43,applesmc
ssb 43517 1 b43
Linux iUbuntu 2.6.32-22-generic #36-Ubuntu SMP Thu Jun 3 19:31:57 UTC 2010 x86_64 GNU/Linux
This didn't work in 9.10 either, but I was hopeful for 10.04.
Both the gui Hardware Drivers and the above posted commandline install method complete without reported error.