I think the topic was how accepting other kids, parents, and teachers would be if a schoolchild's two parents are a "married" gay couple.
In this day and age, there are all kinds of special circumstances. In many casual instances like open house, probably just one parent will be there anyway. It will only be uncomfortable if the couple go out of their way to draw attention to themselves. Some will, and it will be uncomfortable.
Regardless of the marriage/union issues, I don't think being "out" - openly gay - should be commonplace.
Also, Violette, Massachusetts is pretty cool and all, but your reference seems to imply that the state of Massachusetts has "decided" to have gay marriage. No. Four people with robes have decided to use their power to insert their own prejudices into the social fabric.