hahahaha
Apple laptop speakers have been making popping noises on battery power since at least 2003. My 12" PowerBook certainly had the same problem. It's not going to be fixed, it's just a byproduct of disabling power to the speaker amplifier to save battery.
But I'm sure, eventually, a firmware update will be issued to solve this. It just does not sound like it should happen. And it does not only happen on battery power.