As far as I can tell so far you only get the blue light if your Wii receives an e.mail message while in standby mode. So far it is only an e.mail message that will do this. Once you power up the Wii the light turns off and will not come back on once you return to standby regardless of whether or not you read your messages. You can send your Wii an new e.mail message while in standby mode to get the light to return