IKL by Hayes et al. provides a semantics for N3?
One my trip to Duke, just after I arrived on Thursday, Pat Hayes gave a talk about IKL; it's a logic with nice Web-like properties such as any collection of well-formed IKL sentences is itself well-formed. As he was talking, I saw lots of parallels to N3... propositions as terms, log:uri, etc.
By Friday night I was exhuasted from travel, lack of sleep, and conference-going, but I couldn't get the IKL/N3 ideas out of my head, so I had to code it up as another output mode of n3absyn.py.
The superman case works, though it's a bit surprising that rdf:type gets contextualized along with superman. The thread continues with the case of "if your homepage says you're vegetarian, then for the purpose of registration for this conference, you're vegetarian". I'm still puzzling over Pat's explanation a bit, but it seems to make sense.