Dope! The new product is called Hao. It's a handy light specially dedicated to light-writting.
It was designed by French designer Aissa Logerot.
It's shaped like a bottle of spray paint, the LED light can change colors and brightness on the fly and while it's powered by an internal battery that can be charged by shaking of the can.
Wow!
"Graffiti artists can conserve their own gesture they have with an aerosol spray. It is possible to change the color and the brightness of the led to change the graffiti's styles. If the light doesn't have enough battery, the user must shake it to have energy again."
When you spray it, I would assume it isn't permanent. So, tagging wouldn't be illegal!