Color Sensor not allowed in FLL
For any FLL teams using the NXT 2.0 kit, note that the color sensor is not allowed in the FLL competition. The FLL rules allows for up to 2 "Light Sensors", and this refers to only the original NXT light sensor or the older RCX light sensor. The Color Sensor is not allowed, even if you only use it in "Light Sensor" mode. I verified this with FLL to be sure, and they confirmed. So if you have the NXT 2.0 kit, you can buy the original NXT light sensors separately from LEGO Retail or from LEGO Education.