As Nancy Polikoff has noted, Maine recorded a number of "firsts" today. It became the first state to pass marriage equality without first trying a quasi-parallel status such as civil unions. And Maine's Gov. Baldacci became the first governor in the nation to sign a marriage equality bill.
But given the realities of Maine politics, this game is nowhere close to over. Laws in Maine usually go into effect 90 days after the legislature adjourns (somewhere around the end of June). But before that 90 day period is over, opponents of a law can try to gather enough signatures--about 55,000 right now-- to force the measure to a public vote. If opponents get those signatures in on time, implementation of the law will be suspended until a referendum can be held. This provision is commonly known as a "people's veto."