I know a few on my server, but we have quite a small population, and no LGBT-centered guilds that I know of.
I was very flattered to be pegged as trustworthy and open minded enough for one of my guildies to come out to me, I have to say.
Leave your prejudices at the door indeed. Especially for those with a religious argument, aren't part of the teachings that everyone is equal, and you should love thy neighbor? I wasn't aware there was fine print, so it always seemed hypocritical to me.