Why does this matter?
A stay pending appeal would have given Prop. 8 supporters a leisurely ninety days to file a petition for certiorari with the U.S. Supreme Court.
A stay pending mandate means that they must do something within three weeks. Why and what?
Under applicable rules (linked below), the mandate will issue twenty-one days following the Prop. 8 decision. In other words, without further action, the current stay is only good for three weeks.
As a possible next step, Prop. 8 supporters could file a motion with the Ninth Circuit to stay the mandate pending filing of their petition for certiorari.
They could also make this stay request to the Supreme Court, or more precisely, Anthony Kennedy, the justice assigned to the Ninth Circuit. While Justice Kennedy could enter a stay, the lower court must be asked first, "[e]xcept in the most extraordinary circumstances," per Supreme Court Rule 23.
Supporters also have the option to petition the Ninth Circuit for rehearing en banc within fourteen days following the Prop. 8 decision. But, they may wish to bypass rehearing, since an en banc victory in the Ninth Circuit seems unlikely.
As a possible next step, Prop. 8 supporters could file a motion with the Ninth Circuit to stay the mandate pending filing of their petition for certiorari.
They could also make this stay request to the Supreme Court, or more precisely, Anthony Kennedy, the justice assigned to the Ninth Circuit. While Justice Kennedy could enter a stay, the lower court must be asked first, "[e]xcept in the most extraordinary circumstances," per Supreme Court Rule 23.
Supporters also have the option to petition the Ninth Circuit for rehearing en banc within fourteen days following the Prop. 8 decision. But, they may wish to bypass rehearing, since an en banc victory in the Ninth Circuit seems unlikely.
In any case, expect action soon.
FRAP and Ninth Circuit Rules
35 (rehearing en banc deadline same as for rehearing)
40 (rehearing deadline=14 days after judgment)