From CBC NEWS:
The Vatican announced today that blood taken from Pope John Paul II during his final hospitalization will be used as the official relic for veneration after he is beatified on Sunday.
In a statement, the Vatican said four small vials of blood had been taken from John Paul during his final days for a possible transfusion, but were never used. Two of the vials were given to John Paul's private secretary, Cardinal Stanislaw Dziwisz, and another two remained at the Vatican's Bambin Gesu hospital in the care of nuns. One of the hospital vials will be placed in a reliquary and presented Sunday; the other will remain with the nuns.