The National Conference of State Legislatures recently updated a status of where states stand on the issue of same sex marriage, civil unions and domestic partnerships. The tables can be found here.
States that issue marriage licenses to same sex couples: Massachusetts, Connecticut, Iowa, Maine, Vermont, New Hampshire. California passed a law allowing same sex marriage in April 2008, but it was overturned by Proposition 8 in November 2008. Marriages performed prior to Prop. 8 remain valid.
States that recognize same sex marriages performed in other states: Rhode Island, New York, District of Columbia.
States that allow civil unions: Connecticut, Vermont, New Jersey, New Hampshire.
States that allow domestic partnerships, with nearly all state-level spousal rights to unmarried couples: California, Oregon, Washington.
States that allow domestice partnerhsips with only some state-level spousal rights to unmarried couples: Hawaii, Maine, District of Columbia, Wisconsin.
Hawaii is also one of 18 states that offer benefits for same sex partners of state employees. The Hawaii law passed in 1997.