In New York State, I am legally female for most purposes for which a driver’s license is useful, but male for those purposes for which a birth certificate is used. I’m a woman, in a legal marriage entered into under New York law with another woman, though it took three hours to get a marriage license from the New York City Clerk. We file jointly for income taxes, since federal DOMA shouldn’t apply to us. Some states might apply their super-DOMAs to us.
In Texas (a wrongful death action), Florida (a child custody matter) and Kansas (an estate proceeding), legally female transgender women and a legally male transgender man who had valid marriage licenses saw their marriages invalidated by courts. In three states (Ohio, Tennessee, and Idaho), transgender people can’t ever get their birth certificates corrected – and in those states, it’s likely that same-sex marriage is already legal for some couples, much as it has been legal in parts of Texas since 1999.
Federally, I can get a passport as female today, but if I had to change my sex designation for social security after October 2002, I couldn’t.