The text of the letter:
We would like to reiterate the policies first stated in 1995 concerning the submission of names for proxy temple ordinances:
Our preeminent obligation is to seek out and identify our own ancestors. Those whose names are submitted for proxy temple ordinances should be related to the submitter.
Without exception, Church members must not submit for proxy temple ordinances any names from unauthorized groups, such as celebrities and Jewish Holocaust victims. If members do so, they may forfeit their New FamilySearch privileges. Other corrective action may also be taken.
Members are encouraged to participate in FamilySearch indexing which is vital to family history and temple work.
Bishops are asked to post this letter on their meetinghouse bulletin boards. Church members may seek the assistance of the family history consultants in their area for additional information, if needed. Name submission policies are also clearly stated on New.FamilySearch.org.
We appreciate the faithful adherence to these policies by all members of the Church.
Sincerely yours,
Thomas S. Monson
Henry B. Eyring
Dieter F. Uchtdorf
The First Presidency
A letter signed by the First Presidency carries more weight than an ordinary statement from LDS Public Affairs. When the First Presidency speaks, it resonates with prophetic authority.
LDS Church News offers more background. According to Dennis C. Brimhall, managing director of the Church's Family History Department, the conditions of use for the New.FamilySearch.org website are simple and straightforward; namely, that users should not submit the names of nonrelated persons for vicarious temple ordinances, including names of celebrities or famous people, or those gathered from unapproved extraction projects. Chapter 5.4 of the Church Handbook of Instructions Volume 2 is cited as an additional reference. In the final analysis, Church members are best advised to submit for temple ordinances only the names of those verified to be in their direct ancestral line.