This looks like a Solomon-like attempt at splitting the baby along federalist lines. If I’m reading this correctly, the court is ruling that the federal government has to recognize marriages performed in states, including same-sex marriages, regardless of whether the couples’ marriage is recognized in the state in which they later reside.
However, the states don’t have to recognize the marriages, which may make for some confusion at tax time, but otherwise means that couples get non-discriminatory treatment within each level of government. Perhaps that kind of compromise would carry the day at the Supreme Court as well.
Moe Lane clarifies a bit:
Technically, it struck down Section 3 of DoMA, which prohibits federal benefits from being provided for same-sex couples married in states that allow same-sex marriage. Section 2, which allows individual states to not recognize same-sex marriages performed in other states, is still in effect. The whole thing is under a temporary stay until the Supreme Court gets a crack at it; I assume that this will happen… soonish.