The 2200BG and 2915ABG cards use the ipw2200 driver, which is able to control the wifi indicator LED which most laptops will use.
To enable, run the following as root or with sudo privileges:
echo "options ipw2200 led=1" >> /etc/modprobe.d/ipw2200.modprobe
modprobe -r ipw2200 ; modprobe ipw2200
Note that these steps were used with a Dell Inspiron 6000 and Ubuntu 7.10. Certain chipsets may instead use the acerhk module, or need to add the “options ipw2200 led=1” to a different location.