Kevin Vanhoozer has a nice section dealing with the scriptural resignification that takes place as a part of apostolic hermeneutics:
An immediate qualification is in order. Clearly, the passage of Isaiah 53 from which the Ethiopian was reading did not in and of itself generate understanding. The whole point of this episode in Acts 8 is that the eunuch is not able to come to an unaided understanding of the Isaianic text. Philip represents a special kind of external aid, namely, the strategy of reading the Scriptures in their broader apostolic and canonical context…. In short, Philip represents canonical consciousness: the new awareness that the testimony to the God of Israel and the testimony to Jesus Christ belong and make sense together.
It will be objected that Isaiah 53 did not and could not mean what Philip said it meant. But why not? Isaiah, like other prophets, was a spokesperson for God; might he not have said more than he could (explicitly) know? What the divine author intends in Isaiah 53 is seen in the new light of the gospel. Everything is the same, yet different when viewed from the vantage point of the Christ event. The law – or for that matter, history – is not abolished but transfigured; Jewish monotheism, similarly, is not abolished, yet it too is refigured. God has acted mercifully to redeem, yet not in the way Israel expected. There is continuity between the two testaments, to be sure, but a continuity that transcends and transfigures, a continuity that goes beyond mere verbal repetition.
The Drama of Doctrine, pg. 119 (italics in original, bold emphasis mine.)
The language of transformation, transcendence and transfiguration is especially though provoking. The last words – going “beyond mere verbal repetition” – really cuts at the heart of how many evangelicals understand apostolic hermeneutics: “Unless the apostles were (in some sense) simply repeating the theology of Isaiah, they are somehow guilty of lying or misrepresenting the prophet.” Vanhoozer’s entire program, however, provides a much more nuanced (and satisfying) answer to the question of how the NT uses OT texts.