I had to check to make sure today was not April 1 and that the hedline would not send me to The Onion, but here is the official statement from The Pope himself as distributed by Radio Vatican:
I have convoked you to this Consistory, not only for the three canonizations, but also to communicate to you a decision of great importance for the life of the Church. After having repeatedly examined my conscience before God, I have come to the certainty that my strengths, due to an advanced age, are no longer suited to an adequate exercise of the Petrine ministry. I am well aware that this ministry, due to its essential spiritual nature, must be carried out not only with words and deeds, but no less with prayer and suffering. However, in today’s world, subject to so many rapid changes and shaken by questions of deep relevance for the life of faith, in order to govern the bark of Saint Peter and proclaim the Gospel, both strength of mind and body are necessary, strength which in the last few months, has deteriorated in me to the extent that I have had to recognize my incapacity to adequately fulfill the ministry entrusted to me. For this reason, and well aware of the seriousness of this act, with full freedom I declare that I renounce the ministry of Bishop of Rome, Successor of Saint Peter, entrusted to me by the Cardinals on 19 April 2005, in such a way, that as from 28 February 2013, at 20:00 hours, the See of Rome, the See of Saint Peter, will be vacant and a Conclave to elect the new Supreme Pontiff will have to be convoked by those whose competence it is.
In so doing, Pope Benedict is overthrowing a 600+ year old tradition that Popes die in office. And I think it may be the bravest thing he's done in office.
The Catholic Church faces crises that require action: The Vatican Bank scandal, the ongoing fallout from the pedophile priest scandal, declining numbers of priests, and the secularization of Europe. The Church could not afford another lengthy period of inaction and indecision while waiting for a dying Pope to pass away. It needed a younger man. Now.
Pope Benedict thus had the vision and moral courage that John Paul II lacked. While I still regard JPII as the greatest Pope of my lifetime and possibly for much further back than that, he had flaws and clinging to office when he was obviously incapable of performing the tasks was one. His great example of emulating the Suffering Servant easily could have performed in retirement, while a younger man tackled the crises of the day instead of allowing them to fester through the last years of JPII's reign.