The slate app is not beneficial! The point of a slate in a motion picture is the correctly sync the sound and motion. Without a moving piece to snap and make a sound, its pointless. Cool concept though
That was my exact reaction as well. Being in the film business myself, I highly doubt you'll ever see an iPad with that app replace the current system.
Most people think it has something to do with the camera, not the case at all...its all about the snap for audio syncing.
Good call my friend.