From the text of the decision, which is a model of sharp language:
All that Proposition 8 accomplished was to take away from same-sex couples the right to be granted marriage licenses and thus legally to use the designation of 'marriage,' which symbolizes state legitimization and societal recognition of their committed relationships. Proposition 8 serves no purpose, and has no effect, other than to lessen the status and human dignity of gays and lesbians in California, and to officially reclassify their relationships and families as inferior to those of opposite-sex couples. The Constitution simply does not allow for "laws of this sort." [Emphasis added.]
The logic of the decision seems to lean on the fact that California had previously legalized same-sex marriage, and that this right was eliminated by Proposition 8; it doesn't address the broader question of whether it's unconstitutional to deny marriage to same-sex couples in states that have never previously recognized such relationships.
Expect an appeal to the U.S. Supreme Court—which, let's not speculate what they'll do just yet. ◼