Stumbled across Bio2RDF by François Belleau. Here's the blurb:
It is now possible to query Bio2RDF triple store using Sesame's SeRQL query engine. The actual triple store contains all annotations about human and mouse from UniProt, Affymetrix and GeneID. It also contains all GO term definitions and OMIM disease description. It contains 50 millions triples and the native RDF store in sesame weigths 3 Go. Watch for the speed of it ! Thanks for the Sesame team for their great work.
There's a blog, and a SourceForge project. The Bio2RDF website itself displays RDF as tables. It doesn't have a query interface but it's a bit hidden. Try here, based on this blog post.
It uses Seasame, JSP, and SeRQL -- not my favourite technologies -- but is an example of people thinking about RDF and triple stores, and actually making stuff. Must polish up my creaking ant demo and play some more with this.
On the subject of ants, Terry Catapano has been playing with Simile, and come up with this demo.