There is an app called Dark Keys on the market. Its free and it will toggle the keyboard lights on/off for you. Its best to set a short cut key on your keypad. It just makes it easier to toggle the back lights this way. To do this go to
Settings > Applications > Quick Launch and browse letters to place it on the keyboard.
NOTE!!! The short cut uses the search button (the magnifying glass) + any key. For easy use, select the X key, then all you have to do is a 1 thumb operation of holding the magnifying glass and the X key together and there you go. Just a suggestion.
T