A multiple square room, perhaps two long, which drops bombs directly downwards when a target is available. As it simply drops bombs it is only useful if the ship passes over a target below it. However, this also should mean you could layer the whole bottom of a ship with such weapons if you wished, as they would not impede each other as with other weapons such as cannon.
Basically this would allow for ships which specialize in flying high and raining bombs down on land defenses. Perhaps flak guns would also be a good idea for aiming upwards covering 180 degrees.
Yep, definitely planned. :) Either next release or the one after, depending on how things go.