The Human Rights Campaign, a gay rights organization, has released a series of ads featuring celebrities and well-known New Yorkers offering their support for gay marriage. This week's video has Mayor Bloomberg saying, "I'm Mayor Mike Bloomberg. I'm a New Yorker and I support marriage equality because government shouldn't tell you who to love or who to marry."
Mayor BLoomberg has been vocal about his support of gay marriage in the past and has even hinted that his big pockets could convince Republican State Senators to support the issue as well (not really, though—since the State Senate rejected it last December). As for NYC, city clerks offer domestic partnership ceremonies.