In the five years since the LDS church sent busloads of the faithful to California to canvass neighborhoods, and contributed more than $20 million via its members to support the initiative, it has all but dropped the rope in the public policy tug of war over marriage equality. The change stems from an even more remarkable if somewhat invisible transformation happening within the church, prompted by the ugly fight over Prop. 8 and the ensuing backlash from the flock.
Although the LDS's prophet hasn't described a holy revelation directing a revision in church doctrine on same-sex marriage or gay rights in general, the church has shown a rare capacity for introspection and humane cultural change unusual for a large conservative religious organization.
Probably less of an "abandonment" and more of an internal shift that we've been seeing. GLAAD has worked with several LGBT and allied Mormons who are working to change the relationship between the Mormon Church and LGBT people.