HSQL isn't included with JBoss Appplication Server 7+.
You will have to install it yourself.
I've added some simple jdbc functionality into the helloworld-mdb quickstart app, using the org.hsqldb.jdbcDriver. My war file deploys and runs correctly in JBoss 6, but I'm getting a ClassNotFound error for the hsqldb driver in JBoss 7. Can you give me any pointers on how to resolve that? Thanks in advance for any help. --Ian