When Macklemore supports gay rights, it's tacky, but when the "queen of pop" does it, it's genuine and revolutionary? Okay.
Personally, I think this is a great idea (especially if the weddings are legally binding). I mean, imagine the couples, 50 years from now, looking back to when they got married at the Grammys. That would be one hell of a memorable wedding. This is also a huge stepping stone to getting nationwide gay marriage legalized in the US. I definitely support this.