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.