Group marriage?

Writing in the Huffington Post, Elizabeth Marquardt suggests now is the time to get ready for group marriage, by which she means a marriage between more than two people:

Is the prospect of group marriage far-fetched? Probably not. There are several avenues that could soon lead to legal recognition of unions involving three or more people. The efforts come from the fringes of the left, from the darkest corners of the fundamentalist right, and from the laboratories of fertility clinics and hard scientists around the world [more].

Capello tip to Joe Carter.