I'm proud to announce that a federal judge in my state, Wisconsin, just struck down the ban on same-sex marriage.
Does that mean that same-sex marriage is now automatically legal there or do you still need to change the laws to specifically allow it?
In general, if a law is found to be in conflict with the Constitution (federal or state), it is of no force or effect immediately. Sometimes judges will suspend their rulings to give lawmakers time to change the laws, and so that should there be an appeal with a stay granted while the ruling is appealed, anything legally done during the time in between the initial ruling and the stay is not thrown into limbo*.
*It is also sometimes the case that a ruling, even one from the Supreme Court (which cannot be appealed), is suspended because the status quo is better than a legal void while new laws are being written. Look at Canada (Attorney General) v. Bedford--three sections of Canada's prostitution laws were declared invalid, but this was suspended by a year to allow Parliament to pass new laws so that the activity would never be unregulated. (If there's one thing to be said for the virtual dictatorship that is a Westminster democracy, it's that things can get done pretty quickly when they have to be.) Granted, in that particular instance the new law is worse than the old one and will almost certainly be struck down: it's based on the laws used in Sweden, which are probably at least in part to blame for that country's having one of the highest incidences of rape in the world. But the government, being fucktarded beyond belief, refuses to send their proposed law to the Supreme Court for a reference opinion on whether it would actually be constitutional, apparently instead preferring to waste millions of dollars fighting the inevitable court challenges.
