Via ScotusBlog, the Supreme Court has affirmed the lower court ruling that D.C.'s gun ban is unConstitutional.

It looks like it was a 5-4 decision with the usual suspects dissenting. A single majority opinion ruled that the right to keep and bear arms is an individual right. There were two seperate dissenting opinions.

UPDATE: Opinion here.

The Second Amendment protects an individual right to possess a firearm unconnected with service in a militia, and to use that arm for traditional lawful purposes, such as self-defense within the home.

Now for the limits:

Like most rights, the Second Amendment right is not unlimited. It is not a right to keep and carry any weapon whatsoever in any manner whatsoever and for whatever purpose. . . The Court's opinion should not be taken to cast doubt on longstanding prohibitions on the possession of firearms by felons and the mentally ill, or laws forbidding the carrying of firearms in sensitive places such as schools and government buildings, or laws imposing conditions and qualifications on the commercial sale of arms.

But they do give D.C. the smackdown by essentially saying, if D.C. wants to license guns, they must actually issue licenses.

Because Heller conceded at oral argument that the D. C. licensing law is permissible if it is not enforced arbitrarily and capriciously, the Court assumes that a license will satisfy his prayer for relief and does not address the licensing requirement. Assuming he is not disqualified from exercising Second Amendment rights, the District must permit Heller to register his handgun and must issue him a license to carry it in the home.

I would think this applies to cities like Chicago too.

UPDATE2: Here's why John Paul Stevens shouldn't even be a Justice. From his dissent:

The Court would have us believe that over 200 years ago, the Framers made a choice to limit the tools available to elected officials wishing to regulate civilian uses of weapons...

The Founding Fathers were limiting the rights of government?? What were they thinking?