The reference book of men's issues talks about a couple different states and the UK. I just looked at New York, which is clearly gendered against men. And a cursory look at Montana (where the "machete rapist" is from) shows something similar. Marital assault may also be legal in Montana under certain circumstances (for lesser forms of assault), which is kind of interesting, but is probably a fluke.
The pattern I'm seeing is,
A) Rape, the most severe form of sexual assault, applies only to a woman being raped by a man. This is because it's usually defined as a type of penetration. It looks like this is usually a felony.
B) The above would also apply to a woman raping another woman if the rapist uses a finger or an object on the victim. If she forces the victim to pleasure her, exclusively, then it wouldn't count. Same thing for a man raping a man, although this is less universal.
C) There is usually a fairly serious crime of sodomy which doesn't discriminate based on gender (since both genders have a mouth and an anus, but only women have a vagina). This looks like it's usually a felony, but not as serious of a felony as rape.
D) There is usually a lesser crime that does apply to women who rape men, since it is defined in terms of things like sexual contact or touching. This is usually a misdemeanor crime instead of a felony.
There are clear feminist influences that can be found in the emphasis on, and special classification of, sexual assault for the purposes of humiliation or degradation. This follows the feminist theory of sex / rape being used by men to humiliate and oppress women. And it results in a harsher sentence than when the act is performed for sexual gratification alone (which was obviously an oversight by the patriarchy).
I think this is an important point mainly to emphasize the role that feminism has had in defining our (currently sexist) rape laws.
Obviously the problem of men being unfairly discriminated against is a larger issue, but I can't help being curious and pointing this out, either.