Woot!
Here are the compile instructions for UbuntuStudio Jaunty (should work
for any other recent Ubuntu).
wget
http://zynaddsubfx.sf.net/ZynAddSubFX-2.4.0_pre_release.tar.bz2
tar -xvjf ZynAddSubFX-2.4.0_pre_release.tar.bz2
cd ZynAddSubFX-2.4.0/src
sudo apt-get install build-essential fluid libmxml-dev libfftw3-dev
make
To run, go to the same directory and run
./zynaddsubfx
Have fun! Carlo