This workaround, will fix Zend Development Environment issues on Mac OS X Leopard Snow.

In the terminal:

Get the java 5 that was included in 10.5 "leopard" and unpack

cd /tmp/
curl -o java.1.5.0-leopard.tar.gz http://www.cs.washington.edu/homes/isdal/snow_leopard_workaround/java.1.5.0-leopard.tar.gz
tar -xvzf java.1.5.0-leopard.tar.gz

Move it to your System java folder (password needed)

sudo mv 1.5.0 /System/Library/Frameworks/JavaVM.framework/Versions/1.5.0-leopard

Tell OS X that java 5 actually is java 5

cd /System/Library/Frameworks/JavaVM.framework/Versions/
sudo rm 1.5.0
sudo ln -s 1.5.0-leopard 1.5.0
sudo rm 1.5
sudo ln -s 1.5.0 1.5

Open Java Preferences

open "/Applications/Utilities/Java Preferences.app"

Change the properties to use Java 5 32-bit by default: