Check out the summary here.
And here are the "bottom line" what nexts & therefores:
When will we hear? Not for a while. The average time it takes for an appellate court to issue a decision is about 3 months. The Ninth Circuit is particular back logged, so it may be longer.
What are the possible outcomes? There are many. The court could deny standing. Or, the court could assume standing for the purposes of reaching the merits. If the court denies standing, the prop 8 proponents could give up and that would end the case. But, that is unlikely. They would likely ask for an en banc rehearing (basically, another hearing like we had yesterday, but before about 11 Ninth Circuit judges) and if they lose there, they can appeal to the Supreme Court. If the court assumes standing and decides the merits, that decision is likely to be overturned at the Supreme Court.
Can we marry once the court decides? No. Only if the Prop 8 proponents are denied standing and then give up will marriage equality come back to California quickly. Even after the Ninth Circuit decision, we would likely have to wait a few days for official entry of Judge Walker's order.