Did you ever get a response to this question?
I've bumped into the same problem using
JB-2.4.4 petstore1.1.2 and Postgres7.1
I changed ESTORE_DATASOURCE in JNDINames.java and PopulateServlet.java
it now looks like petstore is connecting to the db, but it's now throwing these damn exceptions....
any insite would be quite helpful.