The people have spoken, and their benevolent overlord has delivered!
Seems several of us have been wanting a decent cobblestone generator for a while. While there may be faster, smaller, or more efficient ones, I'm particularly proud of my design! I talked with Ken and Drew in-game, and the decided location is in the nether near the spawn portal.
Operation is quite simple. Flip the power switch on (down) and press the ignition button once. A stream of cobblestone will start to grow in the hallway to the right of the engine.
Glass observation window!
It'll stop generating cobble once the stream of blocks stretches out of the hallway, but the engine will still be running and making noise. When you're finished mining, please turn it off by flipping the power switch up.