Actually, that's really interesting... I'm surprised Notch and the team haven't tried to settle down and port the code to something a lot more efficient. I mean, I can understand why they wouldn't, but Minecraft is pretty unstable... or at least, there's a shitton of room available for optimization. It's not horrible, but there's a lot that could be tidied up. If the team's not careful the project might end up standing on frail sticks and duct tape