A Federal Judge in Virginia ruled that the state of Virginia's case against the federal government claiming the individual mandate is unconstitutional can proceed. The essence of the ruling is that the State of Virginia has standing to bring the case; the burden of proof on the motion to dismiss the case rested with the federal government. In next stages, the burden will shift to the plaintiff, the State of Virginia.
Questions about constitutionality generate lots of interesting debate and discussion...in the end, the ultimate definition of what is constitutional is what 5 of 9 people on the US Supreme Court say it is.
Timothy Jost has the best take, I think here at politico.com blog.
The most consequential aspect of this case, if it continues moving up the court food chain and if applied broadly, would mean that any state could litigate just about anything done by the federal government by simply passing a law contrary to a federal law.