Read in the New York Times yesterday that marriage licences are only supposed to be issued to MA residents, but the town clerks of Provincetown and a number of other towns have said that they will be ignoring this rule and issuing a licence to anyone who wants one. Still not sure if they would allow non-US residents to marry though.
As an aside, in Ontario, non-residents (including as we all know, gay and lesbian couples) can get married, but to get divorced, you need to be a resident for at least a year! Should make for some interesting break-ups!