Works well out of the box in BT4. Not detected by Network Manager though, so I'm just using the terminal to connect it to my network.
Here's how I'm doing it (numbers with stars prefixing is for WPA/WPA2 only):
*1. Create a conf file in /etc called wpa_supplicant.conf
*2. Put the following in the conf file (making adjustments as necessary):
3. Bring the interface up - 'ifconfig wlan0 up'
ssid="YOUR SSID GOES HERE"
psk="YOUR WPA PASSWORD GOES HERE"
4. Scan for open access points (ensures the card is functioning) - 'iwlist wlan0 scan'
5. Associate with AP - 'iwconfig wlan0 essid myssid' (replace myssid with your AP)
6. Set the password for the AP (if there is one)
If you have no encryption: Skip this step.
If you have WEP encryption: 'iwconfig wlan0 key mykey' (replace mykey with your WEP key in hex)
If you have WPA encryption: 'wpa_supplicant -iwlan0 -c/etc/wpa_supplicant.conf -B'
7. Obtain an IP address: 'dhclient'
You should be done. Network Manager won't recognize the connection but everything else seems to work fine.