When you render with Cycles and you want to hide the light emitter you simply uncheck Camera button in object properties under the Cycles Visibility Settings. And you have your light emitted but the emitting object is hidden. That is very useful in many situations. But how we can do it when we render with Corona instead.
I figured out a simple shader setup for it. First create the Corona Light Material and plug it in to the Normal Socket of the Corona Ray Switcher Material which you can find in the Corona Material Menu, after you click Shift+A in the Node Editor. Then it is important to plug the Corona Ray Switcher Material in the Corona Output.
If you still want to have your light emitting object rendered you have to plug the Corona Material in the Direct Socket of Corona Ray Switcher Material.
If the Direct socket is empty, the light source object will not be rendered. Simple.
The shot of my screen shows the example. Pretty simple setup and you get the light still emitting but the emitter object you don't see in the rendered picture :)
At the moment all other options like Reflect and Refract are also switched off.
If you want for example, to see your light source in reflection, simply plug the Corona Light Material in the Reflect Slot of the Corona Ray Switcher Material.
I hope this tip is helpful.