[abyylzzz] Beaming messages by spotlight

Create a means of broadcasting a message via moving spotlights beamed into the night sky (and consequently viewable for miles around).

Morse code is the obvious way, but we're wanting something better, more fluid.  Let the spotlights remain continuously lit, and the message encoded in the motion of the beams.  It's tricky because the motion will be perceived different depending on the location of the viewer.

A different tack: create a method that is machine readable, namely by pointing your cameraphone at the sky.  This will probably simply be a rapidly blinking beam.

Of course, inspired by the Bat signal. The endpoint of a beam may be visible projected onto clouds, or (more vividly) the entire beam reflecting off precipitation or dust.