Fade to Black?

Does there exist a way to fade the entire scene/screen to black?  Or, is there a relatively straightforward way of achieving such an effect?

I wrote an implementation of this in jME a long time ago…I can't remember what it was called…Fader maybe?

There's one, but it only works on a scene node, and not the entire scene.

I suppose that I could just attach it to the root node.

…although the FadeInOut stuff seems to think that you should have separate nodes to fade between.  I just want to fade from there to not there.

I think you can simply pass in null for the second one if you just want to fade-out and null as the first one if you just want to fade-in.