There will be two major differences between the global interfaith prayer for peace which Pope Benedict has called for in Assisi on 27 October, and the two previous ones called by Pope John Paul II in 1986 and 2002.
The first is that the representatives of the different faiths will not actually pray together. After speeches in the morning, there will be "a simple lunch, followed by a moment of silence for individual reflection and prayer," according to the Vatican statement April 2nd. "Later, all those present in Assisi will make a 'pilgrimage' to the Basilica of Saint Francis, in silence, leaving room for personal meditation and prayer". The final part of the Day will include "a solemn renewal of the joint commitment to peace".
It was an open secret that Cardinal Ratzinger, then head of the CDF, opposed the idea of people of different faiths joining in a collective prayer in 2002, so that's one change that could have been predicted.
The other change is more interesting, and surprising. Not only will there be representatives of the world's faiths at Assisi, but also "some figures from the world of culture and science will be invited to share the journey", says the Vatican communique. These are "people who, while not professing to be religious, regard themselves as seekers of the truth and are conscious of a shared responsibility for the cause of justice and peace in this world of ours".
This announcement comes on the heels of the Courtyard of the Gentiles initiative in Parish on 24-25 March, in which there was an attempt at a serious dialogue between Catholics and atheists, bringing together Christian clergy, activists and artists together with nonbelievers from the worlds of politics, economics, law and the arts. (See reports by Sandro Magister here and here.)
If you didn't catch much about it, that's because, as Magister says, it was extremely ineffectively publicised. (I was in another European city, Madrid, at the time, where it passed laregely unnoticed.)
The Courtyard initiative (background here), following news of the Vatican's new "Council for the New Evangelization" (background here), and now the announcement that nonbelievers are to be invited to Assisi, all point to Benedict XVI's papacy opening up a new dialogue front -- with "post-Christian" Europe. By recognizing it as, in effect, a faith, the Pope shows how serious he is about engaging with secularist humanism.