For an interesting and in-depth interpretation of exactly what the California Supreme Court's majority decision means, take a look at this post by jimkeller. The short? Prop 8 sets a precedent where rights can be taken away by a majority vote.

Update: And here, an interesting interpretation that is more optimistic. In short, if this interpretation is true, Prop 8 has been whittled down to mean that it takes away the term marriage but does not take away the right for same-sex couples to enter into a familial relationship which in all ways but name resemble a marriage. Keep in mind that all it says is that Prop 8 does not expressly forbid such marriages-but-not-called-that - it just says that Prop 8 doesn't completely modify the previous decision that banning gay marriages is unconstitutional. Of course, what this marriage-but-not-called-that is isn't discussed.