How is it that Americans rejoice in the killing of another human being?

Osama bin Laden may have been a terrorist, yes, a m murderer but is his killing really something to rejoice over...waving flags in the streets, chanting and shouting? The killing of an 'enemy' shouldn't be a cause for celebration, not in 2011 at least. Where has respect for human life(how ever evil it may be perceived) gone? Do two wrongs make a right?