I think the battle over this is already begun. There is something on the Nov. ballot about changing it back. The whole story is at the link this was about half way doen the page.

Next step: amend the state constitution: California Court Creates Right to Same-Sex Marriage -- 05/16/2008

Conservative organizations, meanwhile, have turned in petitions with more than 1 million signatures in an attempt to get an initiative on the November ballot to amend the state Constitution to define marriage as being between one man and one woman.

If the petitions pass muster, the measure would go on the November ballot. If approved by voters, the amendment would override any court ruling in favor of same-sex marriage.