The Salt Lake Tribune and the Deseret News are reporting an interesting change in the introduction to the Book of Mormon. The introduction to the Book of Mormon, which formerly called the Lamanites "the principal ancestors of the American Indians" will in future editions refer to the Lamanites as merely "among the ancestors of the American Indians." The speculation, which seems accurate, is that this change is a response to recent DNA studies that place the principal ancestors of the Native Americans in Siberia.
The current edition of the Book of Mormon was completed in 1981 (with its introduction, footnotes, cross references, index, and various textual corrections). See here for background. The introduction was most likely written by a committee, though there are still stories floating around that Bruce R. McConkie did it single-handedly.
Whoever wrote the introduction, it does not purport to be revealed and it has never been officially accepted into the LDS canon. It is probably true, however, that the 1981 introduction's explanation of Native American origins accurately reflects what most members of the Church thought about. The fact that the church is making this editorial change without presenting it to the church for a sustaining vote confirms that the introduction was never canon and can be freely changed. The Book of Mormon itself makes no claims about Native American ancestry.
At any rate, my opinion is that this is a good (though fairly insignificant) change for at least two reasons.First, it demonstrates that the Church is willing to accept the validity of scientific research and to reconsider traditional assumptions. Second, it illustrates that interpretations of the scriptures, even an interpretation written and published by the church, are not absolute. Understanding this fact devolves more responsibility on the individual to understand the scriptures through study and prayer rather than take someone else's word for it.