The National Center for Lesbian Rights, based in San Francisco, has filed a petition over Prop. 8, a ballot initiative which deprives LGBT families of the fundamental right of marriage.  The NCLR is joined by a host of other organizations in this petition, including the ACLU and Lambda Legal.  The petition is available in PDF format.

Campaign Petition -- National Center for Lesbian Rights

Discussion about this issue:

The Prop 8 Legal Challenge -- Andrew Sullivan

Is California's Repeal of Same-Sex Marriage an Unconstitutional "Revision" by Initiative? -- Volokh Conspiracy (Eugene Volokh)

Lawsuit filed against anti-gay Prop. 8 in CA -- AmericaBlog.com

Legal groups file lawsuit challenging Prop. 8 -- ACLU.com (Press Release)