Perhaps predictably, posting on the Columbia Federalist Society's blog often turns my thoughts into that way of thinking, albeit in shapes that "real" Federalists probably wouldn't want to touch with a ten foot pole. Today I was looking at their posts on Roper, particularly the echoes of Justice Scalia's disgust at the citation of other countries' practices, and wondering whether there was any federalist justification for taking foreigners into account.
This doesn't quite pass the laugh test, but: I understand that one reason to permit states to go their own way in all matters not specifically reserved to the federal government is that it permits us to see what works and what doesn't. Treating states as "laboratories of reform" means that the feds can look for the best practices and get an idea of what unforeseen consequences might arise. Certainly this kind of thinking played a major role in welfare reform, as states such as Wisconsin that already had begun changing their programs became models for other states, and the government changed to a block grant system to ensure latitude for further experimentation.
Of course, looking at Roper this way doesn't work because federalism only includes 50 states, not hundreds of nations, and the laboratories justification applies mainly to legislation and policy, not judicial decisions on what is Constitutional. Still, if you're discussing Roper with a conservative -- Justice Scalia, perhaps -- and he's not already foaming at the mouth, it might help to say, "You know, Kennedy could have claimed to be drawing on a laboratories-of-experimentation argument under a one-world government..."