I've released version 0.4.4 of the RdfContext gem. As the name implies, RdfContext supports contextual data-stores bound to graphs, along with a ConjunctiveGraph providing the union of contexts within a given data-store.
* Parses RDF/XML, RDFa and N3. RDF/XML and RDFa both pass all relevant W3C test cases (may be run through specs).
* Graph and ConjunctiveGraph with pluggable data-stores. MemoryStore and SQLite3Store both support contexts as well as quoted-graphs and formulae, although no appropriate graph classes yet exist.
* Graphs serialize to N-Triples and RDF/XML.
The gem contains my previously-released rdfa_parser gem referenced from the RDFa Test Harness.