Virtual worlds draw folks from all sorts of religious, cultural and political backgrounds. And the more broad-based they become, the more diverse they'll be. As an example, today I found the "Traditional Marriage Support Center" in Metaplace, created by user HoneyBeeRose.
The info desk helpfully defines "traditional marriage" as "a marriage between one man and one woman, as defined by God in scripture." A slideshow displays various various Bible verses about marriage, and a picture helpfully shows a man and a woman kissing to help illustrate what traditional marriage looks like.
I was actually not aware that traditional marriage needed any particular support, since this is the only kind that is officially sanctioned by most governments of the world. I also have to wonder how HoneyBeeRose plans on supporting traditional marriage in her world. Will their be regular support groups there? Will there be debates between proponents of different kinds of marriage? Perhaps there will be links to resources for people thinking about living in sin or fighting against gay marriage legislation. We'll have to see.
Since anyone in Metaplace can create their own world, I suppose that doesn't prevent someone from creating a "Nontraditional Marriage Support Center" or a "Polygamy Support Center." Note that there is also the "MetaEquality Center" in Metaplace for gays, lesbians, bisexuals and transgendered folk to feel welcome.