The Light falloff possibilities has been improved in Blender 2.46, at least for the Lamp and Spot lamps. There are now two main controls: the Sphere button, and a drop-down list, proposing different light falloff types, as described in this tutorial..
The Lamp lamp is an omni-directional point of light, that is, a point radiating the same amount of light in all directions. It’s visualized by a plain, circled dot, (Lamp Light).