The error in the installation log is:
Feb 22 11:56:28 pippin : BomFileError 12: Cannot allocate memory - ./opt/zimbra/jakarta-tomcat-5.5.7/webapps/zimbraAdmin/WEB-INF/lib/standard.jar
I have made the changes as suggested by Apple for 1. setting Java Preferences to 1.5 and also making changes that affect the commmand line invocation. 'java -version' works as expected.
The message from the installer is unhelpful: 'There were errors - please try installing again'...