The federal court will announce its decision in Perry v. Schwarzenegger, the battle for gay marriage, this afternoon. Chief U.S. District Judge Vaughn Walker of San Francisco will reveal his decision on Proposition 8 at some point between 1 p.m. - 3 p.m.

Matt Baume will be livetweeting from the courthouse and the press conference at @stop8dotorg.

If you'd like to receive a text message with the official decision, text "EQUAL" to 69866 to get a notification the moment the court releases its decision. You can also sign-up for an email alert at equalrightsfoundation.org

If Walker rules against Prop 8, it will (most likely) be appealed to the Ninth U.S. Circuit Court of Appeals in San Francisco. The case could then head to the U.S. Supreme Court in 2011 or 2012.

Same sex marriage supporters will gather in the Castro (at the intersection of Castro and Market) at 5 p.m. then march toward S.F. City Hall. This will be followed by a rally from 6:45 to 8 p.m. Go here for more information.