Mark Kleiman advocates retribution, on the basis of reflection on an extreme case. In general, I am suspicious of conclusions drawn on the basis of extreme cases. Of course, one could question whether Kleiman is right that the punishment of Pinochet would be useless on the grounds of deterrence (he's on better ground in ruling out incapacitation arguments; it seems unlikely that Pinochet will commit further crimes if not locked up); one could argue that such a public case will provide a reminder of the reach of the law and have some benefit in discouraging other criminals, great or petty. But perhaps that is unconvincing.
Of course, on utilitarian grounds (the sort of grounds I like to use), it could also be argued that Pinochet's suffering will make the friends and relatives of his victims happier. Perhaps that's enough justification in this case, since they are so numerous.
Kleiman, however, proposes that making Pinochet suffer is something we owe to his victims, and it sounds like he means the dead ones. I think the idea that we owe anything to the dead is not only false (on utilitarian grounds; we can't benefit or harm them, so we have no moral duties with respect to them), but also dangerous. The idea that retribution for long past wrongs is morally required fuels many a cycle of warfare and oppression. I think we should be trying to break those cycles, starting with the very idea of retribution.