JDO is a datastore-agnostic Java standard for transparent persistence that precedes and is largely a functional superset of JPA. JDO's API & TCK is maintained by the Apache DB project and can be found at http://db.apache.org/jdo. The reference implementation is DataNucleus, which can be found at http://www.datanucleus.org.
This request is to have Cassandra provide an officially supported native JDO implementation or Cassandra plugin for DataNucleus.
There is some past work available on github.com involving JDO, DataNucleus and Cassandra, which might be a good starting point for this work: