"The universe is not required to be in perfect harmony with human ambition."
Carl Sagan (1934 - 1996)
Like the rest of the internet I too am playing Minecraft these days. It's fun, but for me there's too much mining and too little building. For me, it could be a bit more Dwarf Fortressy...
Anyway, back to the geekiness which Minecraft seems to generate in huge amounts: here is a guy who set up a real-time path traced Minecraft.
The absolute best part is at the end; but you're a fool if you don't watch this in full.
If you're a Koopa developer the following should cheer your day: I reworked Koopa's build system so that you can compile everything from a simple 'ant clean all'. Up until now I have been relying on Eclipse and the ANTLR IDE to compile everything for me (minus a few tasks which I did automate). This made it hard for new developers to get going (yes, there actually are a few brave souls who gave it a try). The new system should take away that problem.
Look for the updated system in subversion on sourceforge.