John Piper Responds to N.T. Wright and the New Perspective on Paul (NPP)
John Piper responds to N.T. Wright and the New Perspective on Paul (NPP) in his newest book (due in September): The Future of Justification: A Response to N.T. Wright.
For endorsements see here: #1, #2, #3, #4, #5, #6, #7, #8.
For a summary of the New Perspective on Paul (NPP), see Scott Golike's very clear and helpful talk and notes here.
UPDATE: Dr. Simon Gathercole senior lecturer in New Testament at the University of Aberdeen and recently appointed a lecturer at the University of Cambridge has written an excellent article in Christianity Today explaining and critiquing the NPP. See the article here.
UPDATE #2: The book is now available and Westminster Bookstore has a sample chapter here. The book looks excellent!
UPDATE #3: You can read the whole book online for free at the Desiring God website here!