I had a feeling you weren't giving the whole story since this happened so fast.
They did not change the Constitution yet.
IN FACT, what has happened is that the Mass legislators voted 105-92 to amend the state constitution. But it's at least 30 months from becoming actual law.
***In a 105 to 92 vote, legislators ended a third marathon session of often tearful and impassioned debate to accept a compromise amendment, hammered out by senior Senate leaders, that may alter the nation's oldest constitution in 2006.
Responding to last year's state court ruling that will allow same-sex couples to marry after May 17, lawmakers cleared a first hurdle BUT WILL HAVE TO VOTE on Monday's amendment AGAIN IN 2005 AND put it to a public vote in 2006 before it could become law. (emphasis added by barman)