The AG of Massachusetts is going to sue the Federal Government of the United States over the 1996 enacted Defense of Marriage Act (DOMA). It says that the act is overreaching and prevents the state from administering federal benefits to same-sex married couples in a similar manner to straight married couples.

As far as I am aware, gays are not a protected class under federal law so it probably wont work. Interesting case though
Mass. sues feds over definition of marriage - Yahoo! News