Michael Bird, blogging at Euangelion, has two excellent Easter-related posts that you should really go read.
Thanks, Michael.
Update (2006-04-15): Here's a quote from Carson's essay:
Forgiveness, restoration, salvation, reconciliation -- all are possible, not because sins have somehow been cancelled as if they never were, but because another bore them unjustly. But by this adverb "unjustly" I mean that the person who bore them was just and did not deserve the punishment, not that some moral "system" that God was administering was thereby distorted. Rather, the God against whom the offenses were done pronounced sentence and sent his Son to bear the sentence (Ro 5.8); he made him who had no sin to be sin for us (2Co 5.21). And the purpose of this substitution was that "in him we might become the righteousness of God." (Carson, 134)