I found this selection from Wright (see the whole lecture) to be helpful in clarifying his view on imputation:
The covenant plan of God has what may loosely be called a ‘participationist’ aspect, and this, too, is part of the glorification of God, as I have already shown from Romans 15. Abraham’s true family, the single ‘seed’ which God promised him, is summed up in the Messiah, whose role precisely as Messiah is not least to draw together the identity of the whole of God’s people so that what is true of him is true of them and vice versa. Here we arrive at one of the great truths of the gospel, which is that the accomplishment of Jesus Christ is reckoned to all those who are ‘in him’. This is the truth which has been expressed within the Reformed tradition in terms of ‘imputed righteousness’, often stated in terms of Jesus Christ having fulfilled the moral law and thus having accumulated a ‘righteous’ status which can be shared with all his people. As with some other theological problems, I regard this as saying a substantially right thing in a substantially wrong way, and the trouble when you do that is that things on both sides of the equation, and the passages which are invoked to support them, become distorted. The central passage is in fact Romans 6, and I think it is because much post-reformation theology has tended to fight shy of taking seriously Paul’s realistic theology of baptism that it has sought to achieve what Paul describes in that chapter and elsewhere by another route. The Messiah died to sin; we are in the Messiah through baptism and faith; therefore we have died to sin. The Messiah rose again and is now ‘alive to God’; we are in the Messiah through baptism and faith; therefore we have risen again and are now ‘alive to God’. This is what Paul means in Galatians 3 when he says that as many as have been baptised in to the Messiah have put on the Messiah, and that if we thus belong to the Messiah we are Abraham’s seed, heirs according to the promise. There is indeed a status which is reckoned to all God’s people, all those in Christ; and this status is that of dikaiosune, ‘righteousness’, ‘covenant membership’; and this covenant membership, in order to be covenant membership, must be a covenant membership in which the members have died and been raised, because until that has happened they would still be in their sins. ‘I through the law died to the law, that I might live to God; I have been crucified with the Messiah; nevertheless I live; and the life I now live in the flesh I live by the faith of the Son of God who loved me and gave himself for me’. If this is what you are trying to get at by the phrase ‘imputed righteousness’, then I not only have no quarrel with the substance of it but rather insist on it as a central and vital part of Paul’s theology. What I do object to is calling this truth by a name which, within the world of thought where it is common coin, is bound to be heard to say that Jesus has himself earned something called ‘righteousness’, and that he then reckons this to be true of his people (as in the phrase ‘the merits of Christ’), whereas on my reading of Paul the ‘righteousness’ of Jesus is that which results from God’s vindication of him as Messiah in the resurrection; and, particularly, that this is what Paul means when he speaks of ‘God’s righteousness’, as though that phrase denoted the righteous status which God’s people have in virtue of justification, whereas in fact the phrase, always and everywhere else from the Psalms and Isaiah onwards, refers to God’s own righteousness as the creator and covenant God; and, underneath all of this, I object to the misreading of several key Pauline texts that results, and the marginalisation in consequence of themes which have major importance for Paul but which this theology manages to ignore. The mistake, as I see it, arises from the combination of the Reformers’ proper sense of something being accomplished in Christ Jesus which is then reckoned to us, allied with their overemphasis on the category of iustitia as the catch-all, their consequent underemphasis on Paul’s frequently repeated theology of our participation in the Messiah’s death and resurrection, and their failure to locate Paul’s soteriology itself on the larger map of God’s plan for the whole creation. A proper re-emphasis on ‘God’s righteousness’ as God’s own righteousness should set all this straight. (Bold text mine.)
I think Wright is off the mark in several important areas, not least of which being his weak understanding of the Reformers. (I wonder how much of Luther he has actually read. And I wonder how familiar he is with the Finnish interpretation of Luther, which argues rather persuasively—as least on the main points—that union with Christ (i.e., participation!) is at the heart of Luther’s soteriology and vitally connected to his understanding of justification.) The more I read Wright, the more convinced I become that his “freshness” is dependent to a significant degree upon his caricaturing his opponents’ position (i.e., the traditional view). While I have a massive amount of respect for him as a scholar, this point certainly has the opposite effect! That aside, this selection is important in that it demonstrates that Wright’s disagreement is less in substance than it is in form and expression—at least as he sees it.