That darned whistle
I think I understand the logic, but I disagree with it. The play is what determines what happens, not the physical action of blowing a whistle.
But as every other sport in its right mind knows, if you make the play stoppage point in the referee's head, you take away any chance for review. Had the rule been the whistle determines play stoppage, the Hossa goal (non-goal) could have been reviewed, it could have been determined that the puck was never covered and it could have been heard that the whistle came after the goal.
I'm not saying that the Red Wings would have won last night's game had Hossa's goal been allowed. But last night's play certainly pointed out that the NHL's rule on play stoppage is a poor one.