Catechism of the Catholic Church
http://ccc.scborromeo.org.master.com/texis/master/search/?sufs=0&q=assumption&xsubmit=Search&s=SS
966
"Finally the Immaculate Virgin, preserved free from all stain of original sin, when the course of her earthly life was finished, was taken up body and soul into heavenly glory, and exalted by the Lord as Queen over all things, so that she might be the more fully conformed to her Son, the Lord of lords and conqueror of sin and death." The Assumption of the Blessed Virgin is a singular participation in her Son's Resurrection and an anticipation of the resurrection of other Christians:
In giving birth you kept your virginity; in your Dormition you did not leave the world, O Mother of God, but were joined to the source of Life. You conceived the living God and, by your prayers, will deliver our souls from death."
Annalex and Siobhan are correct, Pyro. She was freed from the corruption of death. Check the following search item in this string for that.
2853
"Victory over the "prince of this world" was won once for all at the Hour when Jesus freely gave himself up to death to give us his life. This is the judgment of this world, and the prince of this world is "cast out." "He pursued the woman" but had no hold on her: the new Eve, "full of grace" of the Holy Spirit, is preserved from sin and the corruption of death (the Immaculate Conception and the Assumption of the Most Holy Mother of God, Mary, ever virgin). "Then the dragon was angry with the woman, and went off to make war on the rest of her offspring." Therefore the Spirit and the Church pray: "Come, Lord Jesus," since his coming will deliver us from the Evil One."
What exactly do you mean by "corruption of death" in this case? Do you mean that she was spared from death itself, or that her body was spared from the ravages of the process of death, and, as the dogma states, was assumed into heaven, along with her soul? I believe that underwent "dormition," meaning she passed into the next life, but she was also assumed. If she is the closest to her Son, and her Son wasn't spared from death, then she would wish to follow her Son in this regard as well.
However, there is also the traditional belief that when Jesus underwent His Passion and Death, Mary underwent a martyrdom of her own, because her heart was subjected to intense sorrows. In light of this, God, her Creator, her Son, and her Spouse, may have spared her from physical death because of this martyrdom. I am no theologian, so I don't know how to resolve these two. It seems to me that St. Alphonsus Liguori believed that she did suffer a martyrdom, and subsequently, many years after her Son's Ascension, she did indeed "fall asleep," and was assumed, body and soul, into heaven