Breaking news! The 9th U.S. Circuit Court of Appeals has denied a motion to re-hear the 3-judge appellate court ruling in Perry v Brown which decided Proposition 8 was unconstitutional on February 7, 2012. The heterosexual supremacists who proposed Proposition 8 now have 90 days to file a certiorari petition before the United States Supreme Court to keep the stay on federal judge Vaughn Walker's ruling keeping Proposition 8 in effect (and preventing same-sex couples from being married). If SCOTUS does grant cert than the stay will remain in effect until the nation's highest court issues a ruling in Summer 2013 on whether it is permissible for a state to amend its own constitution to take away the right to marry that had previously been granted by that state's highest court.
What happened here was that a majority of active judges on the very large 9th U.S. Circuit (25 judges) did not vote in favor of re-hearing the case. Thus the only way other judicial venue for Propsition 8 proponents to go (since the measure has now been found to be unconstitutional at two different levels of the federal judiciary) is to jump to the final court of review, the United States Supreme Court. If the Supreme Court denies their petition, Proposition 8 will disappear from the California Constitution. This decision will probably not happen before the first Monday in October.
The other complicating factor is that this means that in the 2012-13 term the Supreme Court will have two huge gay rights cases before it, Perry v Brown (Proposition 8) and Gill v OPM (DOMA Section 3). These cases are both about same-sex marriage, in two different contexts. The first is whether a state can deny a right which has been previously been given to a minority group. The second is about whether the federal legislature (i.e. Congress) can create a federal definition of marriage for the purpose of denying rights that accrue to married people that a state has decided they should be eligible for.
You can read the full ruling here.
There's also a very helpful diagram explaining the full path of the federal Proposition 8 case to all its possible resolutions.