i personally dont care. not my cup of tea, but i see it this way: more gay people (except lesbians, but ive heard there are more gay men than women) = less concurrence on the women-market. so if they want to merry, let them.
what does it give them next to some respect? does it improve their tax-rates?
and out of curiosity: are they allowed to adopt children (in the USA and elsewhere)?