Most recent changes are about project net.sf.j2s.ajax, which is a AJAX library of Java2Script for both client and server side. And these changes are not about Java2Script compiler.
Current trunk is for Eclipse 3.5. The differences among different versions of Java2Script for Eclipse are two project: net.sf.j2s.core and net.sf.j2s.ui. There are old branches for Eclipse 3.1/2/3/4/6. Branches for Eclipse 3.7/8 and 4.x are not submitted to SVN, as I were planning to separate project net.sf.j2s.core into two project "net.sf.j2s.ast" and "net.sf.j2s.core" but not being finished.
The differences of net.sf.j2s.core among different versions of Eclipse are *.java files in package net.sf.j2s.core.builder. Those *.java files are almost the same with the *.java in Eclipse JDT Core plugin: org.eclipse.jdt.core. If you compare those *.java with JDT's, you will see only package name changes and less than 100 lines changes. So when a new version of Eclipse is released, all we need to do is updating JDT's changes into net.sf.j2s.core.builder and test if it is working as expected or not.