Unless the Judges explicitly put a "Stay" on their ruling, which AFAIK they did not, the law is dead the moment they issued their ruling. However the ruling probably did not extend to keeping and bearing in the Halls of Congress... but then again, maybe it did. It seems to extend only to keeping, and bearing on one's own property, but that's not 100% clear just from reading the opinion, at least to me and on just a quick read through.
Yeah, I think that I should have made it clear to another poster that I was commenting about the basic right, not necessarily whether you can carry a weapon into a government building in particular.
Thanks for the clarification on how a ruling affects a law. I thought I had read that they had some specific time within which to appeal - possibly they do, if so, would assume that's some sort of "conditional stay" that perhaps the judge could issue? You tell me if that's customary.