From an article in the Deseret News:
"The current Introduction page in the Book of Mormon was not part of the original text translated by Joseph Smith, Jr. The Introduction was written and published at the same time additional materials including footnotes and cross references were added in 1981. A one-word change was made to the Introduction in the latest edition of the Book of Mormon published by Doubleday. That change takes into account details of Book of Mormon demography which are not known. The change will be included in the next edition of the Book of Mormon printed by the Church."