It would be nice to take light attenuation into account for point lights.
Here is a common way to compute the attenuation based on two parameters that LightSource could provide:
att = 1.0 / (1.0 + linearAttenuationCoeff*dist + quadraticAttenuationCoeff*dist*dist)
Further info: http://gamedev.stackexchange.com/questions/56897/glsl-light-attenuation-color-and-intensity-formula
Thanks a lot for this extension Daniel :)