- Whether California's Proposition 8, passed in 2008, unfairly rescinded the right to marry (both district and circuit courts have found that it did)
- Whether Clause 3 of DOMA, the mis-named Defense of Marriage Act, is constitutional in banning federal recognition of legally married same sex couples (three different circuit courts have found it is not)
- Whether Arizona acted constitutionally in removing partner benefits from same sex couples.
If they decide NOT to hear the Prop 8 case (technically, if they "deny cert") then marriage will again be equally accessible in the Golden State. Because the Prop 8 appeal to the 9th circuit was found on very narrow grounds applicable only to CA, it is considered a good bet that the Supreme Court will let that decision stand. And don't give me the "will of the people" crap: the Constitution exists in part to protect minorities from the tyranny of the majority. After all, if you had put Jim Crow laws to a popular vote, there would still be drinking fountains labeled "whites only" in the South.
The DOMA cases are very good candidates for a Court hearing because it is a substantive federal question and the law as it stands now differs in different circuits (some finding DOMA clause 3 unconstitutional).
Not sure what the tea leaves are on the AZ case.