Today's SCOTUS ruling is crazy interesting - I find it difficult to believe that no substantive evidence, or certainly not much, has been found that indicates the identification law does not impose a burden on the poor/disabled/old. Of course, there's an inherent methodological problem in trying to prove that - you have to prove the counterfactual that there had not been the ID law, then would have voted. I want to take a look at the briefs and Amicus submitted in this case.
Also, interestingly, though most of the major newspapers suggest that the court's ruling is a sign. win for those who are proponents of ID requirements and that therefore other states are going to have a very difficult time overturning the ruling, I don't think this is the case. The court ruling applies specifically to Indiana in that the the party arguing for overturning the law did not show that in Indiana there had been a significant burden. However, if one could show that there had been a burden in other states, it's very feasible that the court could rule differently there and then the entire thing could just proceed on a state by state basis. That would also present problems, of course.