It's official. Pope Francis has announced that he will canonize both John Paul II and John XXIII, on April 27th, 2014.
The date is quite symbolic. It coincides with the Feast Day of Divine Mercy, which has a strong connection to John Paul II. The Polish pontiff was the first to mark that celebration and he passed away on the day in which the Church celebrated that very Feast Day back in 2005.
At first it was believed that Pope Francis would canonize his predecessors on December 8th, but that date was later moved to April 27th, because milder temperatures will make it easier for pilgrims to travel to Rome.