It sounds like the JBoss deployer doesn't recognize the PostgreSQL data types... make sure you're pointing to the correct datasource in the jbosscmp-jdbc.xml file for the cmp2 example, and make sure the datasource-mapping is set to "PostgreSQL 7.2". If PostgreSQL is your default datasource, you also need to change the datasource-mapping in standardjbosscmp-jdbc.xml (in the conf directory). Other than that I don't know what the problem could be...
I had forgotten a line where it still stood Hypersonic.
Thanks a lot!