This post tells me you either know little about the LDS church, or just have an axe to grind (likely), and don't care to look at why they take the position they take.
I understand that the popular belief is that Mormons hate gay people. Every segment of society is going to have people who do irrational things for irrational reasons, but speaking generally, this isn't the case. In fact, as of late, there has been a lot of emphasis within the church on loving and respecting all people. But you don't have to fully condone someone's lifestyle to be loving or respectful.
The LDS church is particularly defensive of "marriage=man+woman" because it has significant doctrinal implications. It is not because it wants homosexuals to have fewer rights. There are some requirements that must be met in order for a member to have temple blessings (these have eternal implications for followers...) One of them is The Law of Chastity, which states that one must abstain from any sexual relations outside of a legal and lawful marriage. Obviously, in LDS doctrine, homosexuality is a sin. But if a homosexual couple, legally married, follows every other requirement, what is to stop them from demanding that they should be able to participate in these sacred temples, and to possibly even litigate to do so? This is the kind of rock-and-a-hard-place I believe the church is trying to avoid.
This is why my position has always been just like Stoked's. Let "marriage" be the domain of religion, and let the state recognize only civil unions, with equal rights for any couple who becomes one.
