One of the secrets I've kept all along is that I once was a licensed attorney. So, I know a little more than the average bear about the legal goings on, and I went to law school, frankly, because my partner at the time and I could not get the same rights and protections that other opposite sex couples could get simply by saying "I do".
So, I know a wee bit about this area of law since it was my personal area of focus, and I did practice same sex law in a former life (that sounds MUCH kinkier than it was).
The Supreme Court has many ways in which to issue an opinion on a matter brought before it, including a decision not to make a decision at all.
Today's Supreme Court decisions have focused a lot today on whether or not they are allowed to even make a decision. It's a great way for the Supreme Court to avoid making decisions when it wants to. One way is to say that the people who are bringing the suit have no right to. This is the basis by which the Court dismissed the Prop 8 case.
The Windsor case - the tax case - could have been dismissed had Obama actually refunded the estate tax and not simply refused to defend. But because there was harm done to Windsor by the refusal to refund the estate tax paid, the Court had to issue a ruling.
All of the principles I learned in my law school tax classes came down. If Windsor had refused to pay the tax herself, we might not ever have heard the case. ALWAYS pay the taxes first, and then fight the IRS in court. If you don't, you end up in tax court, and there is very little remedy for appeals.
Arcane geeky law stuff.
These cases however open the door and pave the way for further progress.
Basically, the Supreme Court has declared that states have the authority to define marriage, and the federal law cannot discriminate amongst people the state has like-determined. However, this doesn't solve other states which don't recognize marriage, and it doesn't necessarily recognize what another country does unless the state in which they are residing does (Windsor was married in Toronto).
These cases will come, and they will probably be resolved in favor of same-sex marriage, but we haven't gotten those opinions yet.
But this is a positive step. :)