This week, three states passed same-sex marriage laws: Maine, Maryland and Washington. Here is what we were able to determine about when same-sex couples can marry in those states:
Maine: According to the Bangor Daily News: "The secretary of state has 20 days to approve election results and send them on to the governor, Megan Sanborn said. Gov. Paul LePage then has 10 days to certify the results. The law goes into effect 30 days after the governor certifies election results, Sanborn said." Thus, "Same-sex couples in Maine should be able to obtain marriage licenses by Jan. 5 and get married the same day."
Maryland: The only one of the three with an explicit effective date, this law takes effect on January 1, 2013. but "a license is not effective until 6 a.m. on the second calendar day after the license is issued," so presumably couples can get a license January 1, but cannot marry until January 3, 2013.
Washington: This law becomes effective after the election results are certified. According to the Secretary of State, "December 6, 2012 is the last day for the Office of the Secretary of State to certify the returns." There is a three day waiting period after getting a license before you can marry. It appears, then, that the first day to marry is December 9, 2012.
More information on these and other same-sex marriage laws is available at Law About Same-Sex Marriage.