I have one thing to contribute here (plenty of others have said more, just type pope and condoms into Google) and that is on the verbal/written authority structure through which the Church expresses her teachings. This often misunderstood area is one I used to poke fun at Catholics over, until I became one and figured it out. I had to, because in order to do bioethics in the Catholic Church one really needs to be able to tell how authoritative different documents really are.
The first thing to know is that the pope is certainly not automatically infallible in whatever he says – authority is almost always very carefully controlled in its application and scope. The second thing to know is that the papal interview containing this statement has no authority to it; the pope is speaking as a private citizen or perhaps a moral theologian, not as the successor of St. Peter. There is no “interview” category on the hierarchy of magisterial authoritative teaching. It would be the equivalent of a 0) on my list below. However, it does give insight into Pope Benedict’s brain, which is interesting.
Here is my list of how I rank magisterial teaching authority, with a brief explanation, from lowest to highest authority. Now, I renumbered the list a few times and this is a simplification, not the gospel truth, but I believe it is a fair approximation of the levels of teaching authority most of us will ever run into.
0) Papal commission study. For example the study “Communion and Stewardship: Human Persons Created in the Image of God” by the International Theological Commission. This is just an advisory document to the pope, not official teaching of the church. But like an interview it can show where the Church might be trending in the future.
~1) Compendium documents. For example the “Compendium of the Social Doctrine of the Church” by the Pontifical Council for Justice and Peace. These documents are hard to place in a ranking because they are composed of bits from often hundreds of other documents which all vary in authority, from 2) to 6) on this scale. So each teaching within the compendium must be investigated for exactly what teaching authority it actually contains, by examining its reference. Thankfully, that is usually easy to figure out from the footnotes.
2) Papal allocution, that is, a papal speech. Papal allocutions abound and form the basic building block of church authority. Pope John Paul II has about three library shelves of allocutions bound into volumes. Allocutions are important because they tend to appear again as bits in documents of higher authority.
3) Teaching instruction. This is a specific teaching instruction from the Church, for example the Congregation for the Doctrine of the Faith’s 1987 Donum Vitae, which answered specific questions on bioethical issues pertinent to the time. These are often clarifying documents, based on what the Church already teaches, simply extended into more contemporary ethical debates.
4) Papal letter. For example an apostolic letter like Pope John Paul II’s 1988 Mulieris Dignitatem or an encyclical like Pope Benedict XVI’s 2009 Caritas in Veritate. The encyclical is the highest authority level among kinds of papal letters, and is typically the most commonly referenced type of authoritative document. For example, if someone wants to know what the Church teaches on labor, one goes to the social encyclicals like Rerum Novarum or Laborem Exercens. While there are two still higher levels of authority, encyclical will usually suffice.
5) Conciliar documents. These are documents from the ecumenical councils like Vatican I or II. Because they are approved by all the bishops together they have a still higher level of authority than an encyclical. An example would be Gaudium et Spes from Vatican II.
6) Infallible teachings, including both ordinary and extraordinary infallibility. Ordinary infallible teaching are things that have been taught from the beginning of the Church, such as that Jesus is both human and God. These teachings are simply not up for debate, they are core to the faith itself. A lot of these teachings are straight from the bible, as understood through the tradition. Extraordinary infallibility is the least used of all types of authority, having been used, for example, to define in 1950 the doctrine of the Assumption of Mary into heaven.
Go here to get a look at some of the documents available and to see how authority is parsed in practice.
And that is all I am going to say about that.