JOEL - Here is some information I have found about the Mountain Meadows Massacre, taken from the Encyclopedia of Mormonism and other sources.

"In September 1990, some two thousand persons gathered in Cedar City, Utah, to effect a reconciliation among those whose ancestors died or participated in what may be considered the most unfortunate incident in the history of the LDS Church, the Mountain Meadows Massacre. The massacre occurred between September 7 and 11, 1857, when a group of Mormon settlers in southern Utah joined with nearby Indians in killing all but some of the youngest members of a group of non-Mormon emigrants en route to California.

Meanwhile, owing to the lateness of the season, a party of emigrants bound for California elected to take the southern route that passed through Cedar City and thirty-five miles beyond to the Mountain Meadows, which was then an area of springs, bogs, and plentiful grass where travelers frequently stopped to rejuvenate themselves and their stock before braving the harsh desert landscape to the west. Led by John T. Baker and Alexander Fancher, the diverse party consisted of perhaps 120 persons, most of whom left from Arkansas but others of whom joined the company along their journey.

As the Baker-Fancher party traveled from Salt Lake City to the Mountain Meadows, tensions developed between some of the emigrants, on the one hand, and Mormon settlers and their Native American allies, on the other. Spurred by rumors, their own observations, and memories of atrocities some of them had endured in Missouri and Illinois, Mormon residents in and around Cedar City felt compelled to take some action against the emigrant train but ultimately decided to dispatch a rider to Brigham Young seeking his counsel. Leaving September 7, 1857, the messenger made the nearly 300-mile journey in just a little more than three days.

By that time, however, it was too late, and nearly all the men, women, and children of the Baker-Fancher party lay dead. Besides a few persons who left the party before the attack, only about eighteen small children were spared. Two years later, seventeen of the children were returned to family members in northwestern Arkansas. Two decades after the tragedy, one of the Mormon settlers who were present at the massacre, John D. Lee, was executed by a firing squad at the Mountain Meadows, symbolically carrying to the grave the responsibility for those who "were led to do what none singly would have done under normal conditions, and for which none singly can be held responsible" (Brooks, p. 218).

Yet for more than another century after Lee's death, the community guilt of those who participated in the massacre continued to fester alongside the collective pain of both the children who survived it and the relatives of those who did not. Then in the late 1980s, the descendants of those affected by the tragedy began meeting to bind the wounds and achieve a reconciliation. On September 15, 1990, many of them gathered to dedicate a memorial marker to those who died at the Mountain Meadows.

Gordon B. Hinckley, First Counselor in the LDS Church First Presidency, offered the prayer dedicating the new monument. In a talk delivered before the prayer, President Hinckley said he came "not as a descendant of any of the parties involved at Mountain Meadows" but "as a representative of an entire people who have suffered much over what occurred there."

"In our time," he said, "we can read such history as is available, but we really cannot understand nor comprehend that which occurred those tragic and terrible September days in 1857. Rather, we are grateful for the ameliorating influence that has brought us together in a spirit of reconciliation as new generations gather with respect and appreciation one for another. A bridge has been built across a chasm of cankering bitterness. We walk across that bridge and greet one another with a spirit of love, forgiveness, and with hope that there will never be a repetition of anything of the kind." (Excerpts from the talks are all taken from unpublished manuscripts found in the Mountain Meadows Memorial collection, LDS Church Historical Department, Salt Lake City, Utah.)

I suppose there is not a lot of information on this subject mainly because no one seems to know for sure why it occured or what was going on in the minds of those involved. Here are some references that this information was taken from:
Arrington, Leonard J. Brigham Young, American Moses. New York, 1985.
Brooks, Juanita. The Mountain Meadows Massacre. Revised ed., Norman, Okla., 1991.
Comprehensive History of the Church 4:139-80.

ROBLYER - Is is true that Joseph Smith and many of the early leaders were members of the FreeMasons or Masonic Members?

JOEL - Yes, it is true that many early church leaders were Masonic members. Joseph Smith had reason to expect that the Saints might benefit from the network of friendship and support normally associated with this fraternal organization. On March 15 1841, Joseph Smith received the first degree of Freemasonry. By August of 1842 nearly 1,500 LDS men became associated with Illinois Freemasonry, including many members of the Church's governing priesthood bodies.
Joseph Smith participated minimally in Freemasonry and, as far as is known, attended the Nauvoo Masonic Lodge on only three occasions. In April of 1845 Brigham Young decided to discontinue the Nauvoo Lodge of Masons.
Although it is possible Joseph Smith borrowed elements of Freemasonry in developing the temple ceremony, the Endowment is more congruous with LDS scriptures (especially the book of Abraham and the Book of Moses) and ancient ritual than with Freemasonry. Latter-day Saints view the ordinances as a revealed restoration of ancient temple ceremony and only incidentally related to Freemasonry.
The Prophet Joseph Smith suggested that the Endowment and Freemasonry in part emanated from the same ancient spring. Thus, some Nauvoo Masons thought of the Endowment as a restoration of a ritual only imperfectly preserved in Freemasonry.
Resemblances between the two rituals are limited to a small proportion of actions and words. Actually, some find that the LDS Endowment has more similarities with the Pyramid texts and the Coptic documents than with Freemasonry. Even where the two rituals share symbolism, the meanings of the symbols are different.