Today in the Catholic calendar is Corpus Christi, the Solemnity of the Body and Blood of Christ–a day established to honor the Catholic church’s dogma of transubstantiation, the teaching that “by the consecration of the bread and wine there takes place a change of the whole substance of the bread into the substance of the body of Christ our Lord and of the whole substance of the wine into the substance of his blood” (CCC 1376).
Fr. John Z. has photos of the papal celebration in Rome. The photos show the mass, and the procession of the Eucharist through the streets for the worship of the people. Interestingly, all those who received communion from the pope did so kneeling, and on the tongue. Update: Catholic News Service has a story about this, intending to assuage fears, no doubt, that this might become the norm again.
In a related matter, Pope Benedict XVI may set limits on the practice of concelebration.