Nonfiction texts on general postmodernist criticism/theory?
Jameson's book is the only significant one I know about, but I he reduces everything to pastiche, which excludes a lot of art that I would deem "postmodernist"
Postmodern Theory, 1999
Hal Foster (ed.), Postmodern Culture, published by Pluto Classics
It's a series of essays by people like Habermas and Baudrillard, though it doesn't focus on literature but art and culture more generally.
Post-memer-ism more like it!