Interestingly enough, Matt (one of the Motorola Users' Forums Managers) posted a link that Motorola Mobility had posted a "Notification Light Widget" to the Google Play Store. I installed it and it works great, but it was pulled down a short time later. The only time it doesn't seem to kill the light is red flashing low battery alert.
It looks exactly like the other icons in the power control widget--toggle on, toggle off. If you keep searching the Play Store, I'm sure it'll turn up again. Not sure why they pulled it--it's working great for me.