I'm currently reading Stanley Grenz' A Primer on Postmodernism. Grenz is a professor of theology and ethics at Regent College, Vancouver, BC and so speaks from an evangelical christian perspective. The book is true to its purpose (it's a Primer) and so is not big (200 pages including citations and notes). I find his comprehensive treatment of the elements of postmodernism (literary, art, architectectural, social, cultural) accessible with a wealth of citations to pursue further.