There's also the problem of state income taxes and what happens when you file your federal income taxes.
While some states have civil unions and treat them the same as hetero marriage for tax purposes, the federal government doesn't see it that way.
On your federal income tax forms you have to list your state income taxes and include a copy of it. Since the federal gov doesn't recognize gay marriage/civil unions, you are screwed.
I don't know how people in this situation handle it, so they don't get in trouble with the IRS.
Cross-replying. Gotta hate death by taxes