This is a project specifically created for the Google Summer of Code 2009 project Adding RDF Support to the ApacheSolr module (q.v. for more informations; maybe also interesting: this discussion which first introduced the idea).
Its purpose is to allow the Apache Solr Search Integration module to handle arbitrary RDF data. More details will follow once the way to do this has been fleshed out.
The project isn't maintained anymore, since I lack both the necessary time and belief in the module's usefulness. Anyone disagreeing on the latter part may take over the project, if they want.