Property theory is, as I have understood it, first of all characterized by an attempt to approach naive comprehension type-freely and without committing to extensionality. 

There is e.g. the work of Raymond Turner in *A Theory of Properties* in JSL 52(2) 1987 and his monograph *Truth and Modality for Knowledge Representation* (Pitman) 1990 as well as *Semantics and Property Theory* by Gennaro Chierchia and
Raymond Turner in Linguistics and Philosophy, Vol. 11, No. 3 (Aug., 1988), pp. 261-302, plus works cited.


Are there any important new developments of property theory beyond the work mentioned?