I saw this on Andrew Sullivan’s blog, but others are linking as well to the SCOTUSblog where this news came from.

Arguments done. #scotus won’t uphold or strike down #prop8 bc Kennedy thinks it is too soon to rule on #ssm. #prop8 will stay invalidated.

— SCOTUSblog (@SCOTUSblog) March 26, 2013

This means that California will now join the other states in granting marriage equality: a vast step forward.

I dont get the impression from a quick browse that it is quite that simple. The Court is clearly very divided on the issue, and this is from SCOTUS blog:

Supreme Court Justice Anthony M. Kennedy, in an unusually candid process of elimination of options in public, on Tuesday worked his way through the ways for dealing with California’s Proposition 8 ban on same-sex marriage and seemed strongly tempted to just take a pass. He appeared to be troubled about the Court entering “uncharted waters,” on the core issue of who may marry, but at the same time, he also did not look comfortable with any of the other, more limited options. So he openly wondered why the Court had agreed even to hear this case.

Focusing on Kennedy, although that is often the closest one can come to anticipating outcomes on a divided Court, was an even more reliable approach this time given that the other eight Justices were so clearly split: four friendly to same-sex marriage as a constitutional matter, three hostile to it — and, in the end, likely to attract a fourth to that view.

I agree with the question- why did the Court agree to hear this case? And I have one other question- what will it mean to the validity of the decision if it is an extremely closely divided decision? SCOTUSblog elaborates on the possible options. It is a good read.