As I understand it, in the Prop 8 case, there are essentially four options available to The Court:
1. Overrule the lower court ruling and re-instate Prop 8...(Which would mean that gay marriage would remain illegal in California, and the ruling would have no affect in the rest of the country)
2.Hold that the appellants in the Prop 8 case had no standing to bring the appeal, and issue no further ruling or judgement in the case beyond that finding...(Which would mean that the lower court ruling would stand, and gay marriage would be legal in California, but again, have no affect on the rest of the country)
3. Choose the "One Plus Nine" option, which would declare gay marriage legal in California, and the nine other states which have have adopted "civil union" legislation granting gay couples all of the rights available to straight married couples, absent the use of the word "marriage"...
4.Declare the right to marry without regard to gender a basic Constitutional right, and issue a ruling that would strike down every state prohibition against it, and establish a uniform national standard making gay marriage "the law of the land..."
I have not listened to the entire tapes of the oral arguments, but what I have gleaned from fairly objective Court observers who were present at the proceedings...(Like NBC's Pete Williams and CNN's Jefferey Toobin) is that based on the questions and observations made by the Justices, the consensus is this:
That option 2 is far and away the most likely judgement that will be made...
There was little taste for the maximalist position of option 4, which was argued by Ted Olsen and David Boise...(those names may be familiar to you...

) even amongst a couple of the more liberal members of The Court, who expressed a clear desire to decide this case narrowly...
That would appear to be a non-starter with this Court; The Court is not going to use this case to have a
Loving type moment, or view the issue in the same way...
Nor does there appear to be a majority for option 3, (the position argued by The Justice Department) that those states that have granted full rights to "civil unions" must therefore fall under the rubric of "marriage"...
The question was raised by several Justices, (including Justice Kennedy, who is seen as pivotal to forming a majority in this case) that if you arbitrarily imposed legal "marriage" on those states which had granted additional rights to gay couples, (but which had specifically not included the word "marriage") would you be punishing those states, and possibly discouraging other states from also granting those rights? (Which seems like a very fair question to me...)
So that brings us back to option 2...
Today we had the Oral Arguments Re DOMA...
On this one, the proponents of gay marriage would appear to have more of an upper hand, based on the analysis I've followed...
[Laying aside of course the seeming contradiction of arguing one day that gay marriage is fundamentally a guaranteed right within the Constitution; irrespective of the actions of the States, and then arguing on
the very next day, (
literally.... 
though in fairness it wasn't the same folks making the arguments) that "marriage'" should be defined by the States, and that the Federal Government should play no role in the definition...]
From what I've seen on this, there appears to be a clear majority on The Court (to some extent across ideological boundaries) for striking down DOMA on the grounds that the definition of "marriage" should be a State matter....