How to make self contained database dependant unit tests in maven 2?

[Brian E. Fox]

We currently have a system that uses JDO (Kodo implementation) for our
persistence layer. In order to test these persistent classes, I need to
have a JDBC driver and compliant database running. I would really like
to make the process completely self contained like the Maven Wagon
builds. ie download a jar from somewhere that gives me an ultra light db
implementation and jdbc driver and run my tests on it. 
 
Does anyone know if such a thing exists and where I might find it?
Alternatively, does anyone know of any decent file based jdbc drivers
that are open source?
 
Thanks.