I personally think that if two gay people want to marry, it's great. With all the bad things that happen in the world these days, better give a chance to people who want to unite and legitimize their love. Beside, why should they be allowed the same fiscal advantages as regular married couples.
However, this all gets very wrong when those newly formed couples want to raise children. It might not be an easy task (it's never easy anyway), but being legally married, they now have the right to adopt kids. And call my an old-fashioned retard if you will (and I'm only 33!), kids should be raised in a normal, caring and loving context, by a father and a mother. OK if the two loving men or women want to officialize their love, but they shouldn't be allowed to mess with kid's life in the process. There's no doupt the kids will suffer in the process, in school from other kids, from the lack of a true family model, from the lack of a woman figure (or man in the case of lesbians), to only name those.
I already hear people saying that kids get messed up even in "normal" family with a father and a mother. It's true. In my opinion, a lot of inept people should be refused the right to reproduce. We are way too much on this planet anyway. But that's a completely different subject.
So, bottomline is if it only consists of two consenting adults wanting to have their union officialized, I have no problem with that, as long as it only concern those two people and it doesn't mess up kids more than they already are in the process.
My two cents.