They overruled a lower federal court (which had a Clinton appointee BTW). This matches the rulings made in other federal appeals courts, so yes I think there are now two precedents for it. This is a big win for State election laws. The new Federal voting laws of 2002 in response to Florida have proven to be bad IMHO because they've opened up a pandoras box of potential election fraud, just like McCain-Feingold is being exploited. We are much better off with the Federal government (Congress) getting the **** out of the States business and out of the way of political free speech.
Quite honestly, I can't think of any constitutional argument why people couldn't vote for president is several states, if the satate laws allowed it.