Here is the statement from Scott Trotter, spokesperson for the Church:
Today’s decision by the California Supreme Court is welcome. The issue the court decided was whether California citizens validly exercised their right to amend their own constitution to define marriage as between a man and a woman. The court has overwhelmingly affirmed their action.
The Church of Jesus Christ of Latter-day Saints recognizes the deeply held feelings on both sides, but strongly affirms its belief that marriage should be between a man and a woman. The bedrock institution of marriage between a man and a woman has profound implications for our society. These implications range from what our children are taught in schools to individual and collective freedom of religious expression and practice.
Accordingly, the Church stands firmly for what it believes is right for the health and well-being of society as a whole. In doing so, it once again affirms that all of us are children of God, and all deserve to be treated with respect. The Church believes that serious discussion of these issues is not helped when extreme elements on both sides of the debate demonize the other.
----Information from: The Church of Jesus Christ of Latter-day Saints