CNN this week is covering the story of Kirk Murphy a gay man that was in federally funded study regarding gender behavior in the 70's. One of the psychologists called it "sissy therapy". Kirk was punished for any behavior that was perceived to be feminine and rewarded for masculine behavior. His family now says Kirk was never the same after this "treatment". He committed suicide at age 38. Although he identified as gay, he never had a committed relationship.
Conversion therapy has been fully discredited by scientific and medical studies. However, it is still something that some psychotherapist's practice and are still allowed to keep their license. There has been a battle with the California State Association of Marriage and Family Therapists about their refusal to fully go on the record saying these therapies are unacceptable and harmful.
My personal belief is that any therapy that proposes to fundamentally change a person is harmful. Psychotherapy is suppose to be a safe, accepting, and healing place. Teaching someone that they are "wrong" only leads to self loathing and the tragic consequences that follow.