The thought of celebrating the death of a person is really unsettling to me, even if the person was the leader of al-Qaeda. We are all deserving of death. It is only by God's grace we are saved. As Christians, we are supposed to love our enemies and to "pray for those who persecute [us]."
"You have heard that it was said, 'You shall love your neighbor and hate your enemy.' But I say to you, Love your enemies and pray for those who persecute you, so that you may be sons of your Father who is in heaven. For he makes his sun rise on the evil and on the good, and sends rain on the just and on the unjust. For if you love those who love you, what reward do you have? Do not even the tax collectors do the same? And if you greet only your brothers, what more are you doing than others? Do not even the Gentiles do the same? You therefore must be perfect, as your heavenly Father is perfect." - Matthew 5:43-48
In IJM (International Justice Mission) meetings, we have been going through the book, The Good News About Injustice and at one point, we discussed our role in persecuting others even though we, ourselves, are not perfect. God is a just God and will ultimately exercise his wrath on the oppressors and may use other people to do so. But the death of a person who was oppressed by sin, himself, and did not know the gospel is still a loss in God's eyes.
As Christ's body, we should be weeping with God for those who are still bound by sin and may never see the glory of God. Osama bin Laden will not rest in peace, the same way millions (our family and friends) will not rest in peace less they experience and believe the power of God's grace through Jesus Christ. And this is the reason for the Great Commission.
"Say to them, As I live, declares the Lord God, I have no pleasure in the death of the wicked, but that the wicked turn from his way and live." - Ezekiel 33:11