An article by Uwe Michael Lang, taken from his book, "Turning Towards the Lord: Orientation in Liturgical Prayer". Excerpt:
Cardinal Ratzinger is equally emphatic that the celebration of the Eucharist, just as Christian prayer in general, has a trinitarian direction and discusses the question of how this can be communicated most fittingly in liturgical gesture. When we speak to someone, we obviously face that person. Accordingly, the whole liturgical assembly, priest and people, should face the same way, turning towards God to whom prayers and offerings are addressed in this common act of trinitarian worship. Ratzinger rightly protests against the mistaken idea that in this case the celebrating priest is facing "towards the altar", "towards the tabernacle", or even "towards the wall". The catchphrase often heard nowadays that the priest is "turning his back on the people" is a classic example of confounding theology and topography, for the crucial point is that the Mass is a common act of worship where priest and people together, representing the pilgrim Church, reach out for the transcendent God.