What a wonderfully happy day! But, of course, you can't turn up empty-handed. It's traditional to take a gift for the grooms, as it is in any marriage.
As the idea of gay weddings is so new in our society, the mall stores may be hurrying to keep up with the demand. The internet is already well ahead.
This collection of wedding gifts for two grooms focuses upon the fact that this is a gay marriage. By giving a nod to that, you are tacitly registering your support for all of it, not merely the big day.