There are some interesting things happening on the periphery of these cases as they come to trial. I can best sum it up, with no malice intended, as rats fleeing the sinking ship.  California Governor Jerry Brown and Attorney General Kamala Harris have declined to defend Prop 8, leaving only it's staunch conservative backer Dennis Hollingsworth, the case's namesake defendant, of ProtectMarriage.com, to carry the ball. In 2011 many key legistaltors and the Obama administration turned on DOMA, as far as determining that section 3 was unconstitutional and the DOJ would not defend it. In its place the House General Counsel under directive from the Republican congressional leadership would defend the law. Senators. Claire McCaskill, D-Mo., John “Jay” Rockefeller, D-W.V., and Mark Warner, D-Va., said 3/24 and 3/35 that they no longer support a federal law banning gay marriage.

PROP 8: If the court does not side with Hollingsworth, the ruling reverts to an earlier decision which struck down Prop 8. The case originated with Kristin Perry, who was denied a marriage license in Berkeley. Kristin and her partner, Sandra Stier, are mothers of 4 children. Perry has an interesting legal team, Theodore Olson and David Boies, who have a history of going at each other in high profile cases.
On the against side: Olson has 20 minutes to state his. They'll focus on arguing that "marriage is a fundamental right that has nothing to do with having children. … Because marriage is such a fundamental right, and gays and lesbians have traditionally been victims of discrimination, the challengers continue, the Court should apply a more demanding test – known as 'heightened scrutiny' – to determine whether Proposition 8 is constitutional.".  Then Solicitor General Donald Verrilli Jr. will then have 10 minutes to explain why the Obama administration believes Prop 8 should go away. From the Times:

"The government will argue on grounds referred to as the "eight-state solution," which would apply only to states where gay marriage is banned, but same-sex civil unions are allowed (California, Delaware, Hawaii, Illinois, Nevada, New Jersey, Oregon, and Rhode Island). Verrilli will argue that this violates the equal-protection clause of the Constitution. That case has been called "quite modest," while others have argued, "If the Court takes the President's argument seriously, the justices need not stop at just 8 states. The President's theory could invalidate all marriage discrimination against gays."

On the pro–Prop 8 side: Hollingsworth will have 30 minutes to make his case. If found to have standing, they will argue that "traditional" marriage should be preserved so that children "will be born and raised in stable and enduring family units by their own mothers and fathers."

Verdicts of this could be very little to very dramatic, if the court upholds the defeat of Prop 8, all bans on same sex marriage could be constitutionally challenged, or it could be that a narrow ruling that "once a right is given it cannot be taken away by the state." It bears remarking, "There is no possibility that the court would ban same-sex marriage in places that choose to permit it."

DOMA, enacted September 21, 1996 defines marriage as the legal union of one man and one woman for federal and inter-state recognition purposes.
Section 3 of DOMA has been found unconstitutional (as it violates the equal-protection clause of the Fourteenth Amendment) in eight federal courts, including the First and Second Circuit Court of Appeals, on over 1,000 right issues that married couples enjoy. Such as bankruptcy, public employee benefits, estate taxes, and immigration. 

The U.S. Supreme Court has agreed to hear an appeal in one of those cases, United States v. Windsor, and scheduled oral arguments for March 27, 2013. Edith Windsor was forced to pay $363,053 in estate taxes after her partner of more than 40 years died.
From the Times:"If the court is to establish a constitutional right to same-sex marriage, it will be in [the Prop 8 case] and not in a narrower one to be argued on Wednesday about the federal Defense of Marriage Act,"

Likely outcomes will be for DOMA to fall and Prop 8 to be more narrowly refined and not completely thrown out.
The judges have their work cut out for them and a nation of of men and women who love each other and want the natural right to express their love for whomever they want, will be watching and waiting. Final decisions are expected to be revealed in June.