To make things even more bizarre, if I run an instance of Eclipse with the same configuration as the default instance from within eclipse (i.e. There is a classes.jar file at /System/LIbrary/Frameworks/amework/Versions/1.4.2-l eopard/Classes The 1.4.2 JRE in the preferences page points to /System/LIbrary/Frameworks/amework/Versions/1.4.2-l eopard/Home System/LIbrary/Frameworks/amework/Versions/1.6.0/C lasses However, when I create a new project, the JRE System Library container, while still called, gets its jars from the Java 6 home. I can even set the 1.4.2 JRE to be the default workspace JRE.
Currently, Eclipse properly detects that there are two different JREs on the machine, and points to their proper location in the Preferences -> Java -> Installed JREs preference page. I am currently running the latest standard download of Eclipse for Java EE Developers. I have installed the 1.4.2 JRE from Apple on my Mac, currently running Snow Leopard.