The argument is, whether this is a constitutional amendment (that can be voted on solely by the people) or a revision (that requires a vote by 2/3rd of the California legislature).
Now, given that they didn’t stay the decision gives us some hope. After all, if they had stayed the decision, that would seem to indicate that they automatically agreed to Prop 8 opponents. Now, they have till March 8th to bitch and moan about not getting married.
I would think that the People of California trump the Supreme Court of California so long as what they passed doesn't violate the US Constitution.