According to today's Boston Globe, the City of Cambridge will open the doors of its City Hall at 10:30 p.m. on Sunday May 16 to same-sex couples wishing to be married, and will begin accepting marriage intention forms at the stroke of midnight at the start of Monday May 17.
"Cambridge's early opening does not mean that couples can get married on the spot. State law stipulates a three-day period from the time they apply with a clerk's office until they can pick up their license and be married, though a judge can speed the process by waiving that three-day watting period."