An extremely good book:
Fear of Knowledge: Against Relativism and Constructivism, Oxford University Press 2006 -
short, on a very important topic, written almost without any technical terminology, extremely clear, and very convincing. Even those without a background in philosophy should find it readable.
Also, this essay: http://plato.stanford.edu/entries/nonidentity-problem/ gives a good example of where philosophy is now. A clear relatively simple problem, many competing approaches, each approach has clear difficulties, and [therefore] no resolution.