The Supremes have ruled...

Well, at a minimum you need to listen to the first twenty seconds :)

From a libertarian perspective I don't think government should be involved in marriage in the first place, we as a species are certainly beyond needing to incentivize procreation.  If churches want to perform same-sex marriage, or not, they should be permitted to do so regardless of the State, or state that they are located in.  If two or more parties wish to enter into a civil contract vis-à-vis group property allocation and distribution, medical decision making, powers of attorney, etc. they should be free to do so free from government interference or oversight.  Governments role in marriage should extend no further than enforcing the associated civil contract (a legitimate function in a free society) the terms of which should be none of the governments concern.

That said, with 37 states legalizing gay marriage:

Alabama, Alaska, Arizona, California, Colorado, Connecticut, Delaware, Florida, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Maine, Maryland, Massachusetts, Minnesota, Montana, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin and Wyoming.

I don't think the court should have ruled otherwise, although they could have waited for 38... a majority sufficient to be considered a de facto majority for a constitutional amendment, but legally and technically I believe it to be the correct decision under the 14th amendment which the court has previously (and in my opinion incorrectly... which could be a blog post unto itself) recognized as the law of the land.

Section 1. ... nor deny to any person within its jurisdiction the equal protection of the laws.   

While I agree with Justice Scalia's assessment that:

The opinion is couched in a style that is as pretentious as its content is egotistic

And in deference to Justice Scalia esteemed legal opinion...

If, even as the price to be paid for a fifth vote, I ever joined an opinion for the Court that began: “The Constitution promises liberty to all within its reach, a liberty that includes certain specific rights that allow persons, within a lawful realm, to define and express their identity,” I would hide my head in a bag.  

The Unknown Comic