The decision is here if you have the desire to slog through it. There is little need. The conclusion is that opposition to Proposition 8 is based in tradition and has no place in modern legal argument.
Judge Vaughn walker has magically discovered a right to gay marriage within the Constitution because there is no rational basis to define marriage as between a man and a woman. Whether this means Vaughn has, as has been speculated by gay marriage opponents, opened the door for marriage based solely on the criteria of consenting adults--polygamy, marrying your sister--sounds unlikely, but his opinion is a sloppy example of interpreting the Constitution as a living, breathing document that must change with societal mores.
Such is never an exact science, so expect the United States Supreme Court to jump on this one immediately. At the very least, we will finally find Elena Kagan's definitive opinion on gay marriage.