The so-called "extraordinary infallibility" of the Pope is not automatic in the Catholic church, but rather, only when he issues a command ex cathedra. The so-called "ordinary infallibility" applies under a sort of consensus decision with Catholic clergy on dogma and practices (ie, abortion is unacceptable, only celibate men may join the priesthood, et al).

When Benedict issued his statement about the Latin mass, neither condition of infallibility applied, but since he is the leader of the church, it's a good bet that the dust will be coming off a lot of the old Nova Vulgata Bibles.

Was hidden into a linked link, but here you go: "For this reason the Second Vatican Council states that all the Pope's teaching should be listened to and accepted, even when it is not given ex cathedra but is proposed in the ordinary exercise of his Magisterium with the manifest intention of declaring, recalling and confirming the doctrine of faith. It is a consequence of the institutional fact and spiritual inheritance that completes the dimensions of the succession to Peter."
It seems pretty clear to me.
http://www.vatican.va/holy_father/john_paul_ii/audiences/alpha/data/aud1...