A couple of days ago I did a massive refactoring in a couple of components of blueBill Mobile; the ones related to the management of fact sheets (e.g. bird calls with metadata) that I was talking about in a previous post. The first implementation (in the latest release) was based on RDF triples and used an ad-hoc implementation of a RDF+JSON serializer; now I can say I'm successfully running some modules of OpenSesame, so I got rid of a bunch of my own code and - above all - I'm able to generate and parse RDF+XML and RDF+N3 too. BTW, the RDF+N3 parser seems to be much faster than RDF+JSON, thus I probably don't need the latter any longer.
Googling around one can find traces of people trying to use an RDF store on Android - so far I've mostly found people talking of Jena ports. What I like of OpenSesame is that it's released in many small and self-consistent modules, that made really easier for me the integration of what I need so far (and I'll be probably able to incrementally integrate other parts).
At the moment I'm not using any backing database, but the simplified in-memory Graph object together with a few serializers. I'll investigate about the backing database after the next release (end of July). I didn't have to change the sources of OpenSesame, but needed to do some patching to work around some XML problems with Android (as usual: missing stuff).
This is just a teaser since I didn't find the time so far to post a more comprehensive article: expect one soon here or at DZone.