Here is the link to a FREE PDF copy of John Piper's newest book on Justification (written in response to N.T. Wright). For me, I think both have good things to say. While Piper gives a solid reinforcement of the traditional (and I think Biblical) view of Justification, Wright adds valuable insights that challenege the church to recognize some of the broader implications.
The Future of Justification: "The Future of Justification on DesiringGod.org"
Here also is a link to some essays on Justification by N.T. Wright