Some quick thoughts about this week's (potentially) historic week at the SCOTUS:
1) DOMA is clearly unconstitutional, on 14th Amendment grounds at least. Probably 10th as well. I wouldn't be surprised to see the four liberal justices rule against on the basis of the 14th, with Kennedy (and maybe even Roberts) concurring on 10th Amendment grounds. (I suspect a few of the more level-headed Republicans in congress will live to regret not repealing DOMA when they had the chance.)
2) Chief Justice Roberts' criticism of Obama enforcing DOMA while refusing to defend it in court is valid insofar as one might expect that the President's obligation to uphold the Constitution implies that he ought not enforce laws he genuinely believes to violate it. But of course, had Mr. Obama "the courage of his convictions" he would be roundly (and perhaps rightly) criticized for taking on the role of arbiter of the Constitution, one properly reserved to the judicial branch. In other words. he cannot really "win", here, regardless of what he does. I think the middle course he has charted here is the most prudent, if not the most courageous.
3) Proposition 8 is trickier. It is rather difficult to argue on one hand that DOMA constitutes federal overreach, but that the State of California does not retain the right to determine family law on the other. The way out is of course that Prop 8 also violates the Equal Protection clause. Personally, I think it does. However, I think the Court's aversion to issuing a sweeping ruling that will effectively legalize same-sex marriage nationwide will carry the day. Either Prop 8 gets upheld, narrowly (i.e., in such a way that only affects California) or they dismiss it on the basis of standing.
Between those two, I'd prefer the latter, because that would at least (re)-legalize extant marriages in California.
4) Despite the Court's aversion to another Roe-like ruling, I think they would do both the Republicans and the country a huge favor by effectively ending the substantive policy debate nationwide. Otherwise, we're looking at years of state-level fights on this and the Republicans will have little choice but to own the issue until the current crop of pissed-off old white guys dies off.
That is, of course, no basis at all on which to rule on constitutionality. But there it is.