In Piper's article "Jesus, Islam, Pharisee, and the New Paul Perspective", he cites that N.T. Wright doesn't believe that Pharisees were a "religion of of legalistic works-righteousness".
"Then, there is Wright’s affirmation of Sanders’ claim that the religion of the Pharisees was not the “religion of legalistic works-righteousness,” and that the “The Jew [of Jesus’ day] keeps the law out of gratitude, as the proper response to grace.” The only explanation I can find for such amazing statements is that the testimony of Jesus is denied or obscured. It is my impression that evangelicals enamored by the NPP have not reckoned seriously enough with the fact that the origination of the NPP seems to have taken place in the halls of such denial or obscuring."
So does Wright believe that Pharisees are not legalists? Again like Piper's Taste and See article from last week in regards to Chris Corcoran, Wright's opinion of the Pharisees is more nuanced that I think Piper anticipates.
Wright states in an interview:
"As a Pharisee (Paul''s perspective), he believed that, once people came into God's covenant by grace, they were to be marked out in the present time, ahead of the final judgment, by their possession of and their attempts to keep the Jewish law, the Torah. As a Christian, he believed that once people came into God's covenant by grace, they were to marked out in the present time, ahead of the final judgment, by their belief that Jesus was Lord and that God had raised him from the dead. To characterize that Pharisaic view as "works-based salvation" is clearly a gross oversimplification and confusion. It is clear to me that (a) most Jews whose views we can track at the time-an important qualification-believed that God called them to be Jews, Israelites, through his covenant actions in the Exodus, etc., fulfilling the promises to Abraham and his seed, i.e. by grace, not by their own works (b) most Jews believed that there would be a final judgment at which their works in the present time would be an important part, if not the whole part, of what counted and that in this respect early Christians like Paul agreed with them; and (c) most Jews believed that you could tell in advance who would be vindicated at that final judgment because they possessed Torah and tried to keep. I say "tried to keep it" because they knew that, if they failed, there were sacrifices to cover such sins. What Second Temple Jews held (to overgeneralize to make a point) was a works-based present justification, and that is what Paul was attacking." 
 Criswell Theological Review (Spring 2005)