Jeni, marvellous that you're working on this, and marvellous that you've thought this through an awful lot already.
I can't offer any real practical suggestions right away (a lot to digest here!) but one question I think right away may some significance: you want this to be friendly to normal developers - what kind of things are they actually used to? Do you have any examples of existing JSON serializations of relatively complex data structures - something to give an idea of the target. While it's a bit apples and oranges, there presumably are plenty of systems now pushing out JSON rather than the XML they would a few years ago - is there anything to be learnt from that scenario that can be exploited for RDF? Cheers, Danny. -- http://danny.ayers.name