It looks like HP have a project called Genesis which maybe an all Java triple store for RDF or maybe it's just a better interface to existing SQL databases, BDB, etc.
The first email that tweaked me was:
"Preview3 is due to be released in May and will include databsae backed persistent storage (provided by the HP Genesis team). The current preview2 support in-memory RDF models only."
The features that it may have are:
"1. Peer-level ingest and publish. This is the server to server interface mentioned previously. In this interface each server owns its own data and is not responsible for the data in its peers.
2. Priveleged peer-level based on one or more of data replication, mirroring, and federation. In this interface each server cooperates to present an interface to a logically combined metadata store."