Translation from New Liturgical Movement:
The Midnight Mass will be preceded by a short prayer vigil which concludes with the Kalenda, the Christmas Proclamation, which had heretofore been included in the Mass itself, whereas Msgr. Marini notes that this placement corresponds better to its nature, since the "Roman Martyrology foresees the singing of the Kalenda on the day of the vigil of Christmas at the end of Lauds or of a Little Hour of the Liturgy of Hours".
The Holy Father will not wear cope and mitre for the Urbi et Orbi blessing, but choir dress. To forestall any rash comments, this is not without precedent, as may be seen from the accompanying picture of Pius XII imparing the Urbi et Orbi blessing on Easter 1952. The choice would seem to be connected to the fact that the Pope does not publicly celebrate the Missa in die, and is therefore not vested prior to the blessing. Msgr. Marini explains that it is "a solemn benediction which is not connected to a particular liturgical rite."
After Pontifical Vespers on 31 December there will again be Eucharistic Adoration to signify, in the words of Msgr Marini, "the centrality of adoration in the life of the Church and of the disciples of the Lord."
Pope Benedict will wear a Roman chasuble for the Mass of the Epiphany.
The Mass of the Baptism of the Lord will again be celebrated in the Sistine chapel ad orientem. As Msgr. Marini explains "this means that at some points the Pope will turn towards the Crucified, thus underlining the correct orientation of the Eucharistic celebration. This is not about turning the back to the people, but about assuming the same orientation as the assembly, which precisely looks toward the Crucified."