2nd gen G5 iMacs and later have an ambient light sensor that will adjust the brightness of the light depending on the ambient light in the room. 1st gen G5 iMacs don't, but you can install the Firmware update on them to make the brightness of the light vary with the time of day. As long as the system time is set correctly, your iMac is really only waking you when you're supposed to be up anyway...
Other than this, the tape works nicely.