Something that grew out of a comment discussion is a statement the Pope made today about non-Catholic churches. This is a good document, not necessarily in the sense that it's a joyful or happy document, but in the sense that it addresses some critical questions.
Its purpose, in part, is to reiterate and explain why Protestant communities are not "churches" in the proper sense of the term (and why Orthodox churches are). Specifically, because churches have true sacraments and above all – because of the apostolic succession – the priesthood and the Eucharist. These are seen as essential to the term "church" as we use it. I see it as a semantic nuance. It doesn't mean that people can't be saved in these churches, only that these churches don't possess some elements Catholicism considers to be essential to "churches" per se. One can argue about the semantics. I personally think this is an arbitrary distinction to make; I understand the definition, but I don't fully understand the rationale behind the distinction. Still, I fully respect and support it.
One point to make is that Catholicism and Orthodoxy believe that the church is an organ by which grace and salvation are communicated, mystically, to Christians. It's like a mother nursing her child. For a lot of Protestants, my impression is the church is just a place where believers hang out, nothing more. It's a convenience, it's helpful, it's even important, but it doesn't play an essential role in salvation. They are just radically different views. So you can see how Pope Benedict would want to clarify the term. I even note that the Assemblies of God does not call itself a church (at least in its name), and neither does the Southern Baptist Convention, and many other Protestants are going the same way.
A few other interesting points.
It affirms that Second Vatican Council did not change the teaching on the nature of the Church.
It explains what SVC means by "The church of Christ subsists in the Catholic Church", and why the term "is" was not used. In this part it says "It is possible, according to Catholic doctrine, to affirm correctly that the Church of Christ is present and operative in the churches and ecclesial Communities not yet fully in communion with the Catholic Church, on account of the elements of sanctification and truth that are present in them."
It's a short read so I encourage you to read it. I do note that the news article I read made reference to things not in this document (the "woundedness" of the non-Catholic churches) and claimed it was 16 pages in length (which this document can't be) so I'm not sure what's going on. I know this is the only document of this kind on the Vatican website.