If that's not the case, we'll head back to bed and keep an eye out on Thursday, the next day the court will be issuing opinions. Here's a SCOTUSblog FAQ about how the court issues opinions. SCOTUSblog, the gold standard in high court watching, thinks the same-sex marriage opinions won't be issued until the last week of June.
Prop 8, of course, is California's same-sex marriage ban that was struck down on narrow grounds by the 9th U.S. Circuit of Appeals. Should SCOTUS uphold that decision, same-sex marriages could begin again in California within a month, according to San Francisco City Attorney Dennis Herrera's office. (San Francisco was an intervenor in the case on the plaintiff's side.) If the court uses the case to issue a more sweeping ruling that all same-sex marriage bans are illegal, that would effectively legalize same-sex marriage throughout the country.
DOMA is a 1996 federal law that defines marriage as only between a man and a woman. It prevents those who are in same-sex marriages from receiving a host of federal benefits, such as the ability to file a joint tax return. In the case before the court, a widow was forced to pay $363,000 in inheritance taxes after her female spouse died, a liability she would not have incurred if she'd been married to a man. A federal appeals court ruled that provision of DOMA was unconstitutional. Another provision, requiring states to recognize only opposite-sex marriages performed in other states, is not at issue here.