In another law with roots in the colonial era, Massachusetts does not recognize common-law marriage entered to within its borders. That is, de facto marriages without a license or ceremony, in which the couple simply presents themselves as married. However, it does recognize common-law marriages that were legal in the states.
Currently, those other states are:
District of Columbia
Georgia (if created before 1/97)
Idaho (if created before 1/96)
New Hampshire (for inheritance purposes only)
Ohio (if created before 10/91)
Pennsylvania (if created before 9/03)
This is an interesting wrinkle on the full-faith and credit clause under which the 50 states and the District of Columbia recognize each other's laws. The DoMA states are weaseling out of this long-standing practice for same-sex marriages.