A piece at CT examines the results of text-criticism that suggests that John 8 (The woman caught in adultery. Pericopae adulterae) is probably a later addition to the Gospel.
It's not like this is a new discovery. It's a standard footnote in the NAB, I believe. I recall reading about this in my intro classes in grad school.
But what does it mean that the earliest manuscript evidence does not have this story? Well, if one holds to Sola Scriptura, this is a puzzle indeed. One ends up saying things like: "This is canonical but not inspired." (The Holy Spirit just kinda bypassed this part of your Bible?) And Christians should be wary of praying this passage, or studying it, or quoting that oft-quoted, beloved line, "Let him who is without sin cast the first stone."
I'm reminded of an important point Luke Timothy Johnson made in his fantastic "The Real Jesus: The Misguided Quest for the Historical Jesus and the Truth of the Traditional Gospels." (I can't recommend this book enough. It's an easy read, and one doesn't have to be an expert or a scholar to follow.), that philosophically, the modern "quest for the historical Jesus" goes back before Hermann Samuel Reimarus (where textbooks draw the line between the dawn of critical reason and pre-critical darkness and superstition), to the introduction by Luther of the principle of sola Scriptura. Once you have this in place, along with the Reformation impulse to find the proper, primitive, pristine, pre-Catholic Christianity, pure and undefiled, you are on your way to relying on a historical reconstruction to find out what Jesus "really" did or said, and a class of historian-priests who are the guardians of the "truth about Jesus." He makes the point that history simply doesn't give us enough. What we have at the very beginning are a few scattered letters and this four-fold portrait, which the Church has ever upheld since. That's our beginning. That's all we really have. And, that's all we really need ...
For Catholics (and Orthodox; while they might not recognize Trent, they're hardly going to be tempted to go down the road our Reformed brethren are wont to), the matter of the canon is itself a dogma, magisterially defined in Council, and not open to revision or discussion. Implicit is the understanding that the canon of scripture is a product of the Church, acting under the guidance of the Holy Spirit.
So, the next time John 8 rolls around in the lectionary cycle, don't worry if your pastor or deacon delivers a wonderful homily on this eminently Christian story.
[The interview with Daniel B. Wallace, the executive director of the Center for New Testament Manuscripts is definitely worth reading. The Center's mission is to photograph and digitize all known Greek New Testament manuscripts (that's 1.3 million manuscripts), early translations and Patristic commentaries), surely a worthy effort. In the interview, Wallace talks about his recent visit to Tirana, as part of a team of the first Western scholars granted access to photograph manuscripts in the Albanian National Archives. The Center's website.]