Stephen Bainbridge, a law professor at UCLA, presents an interesting Catholic perspective on whether Saddam should have been executed. Despite my conflicted feelings about the death penalty, I do not think it was wrong to execute Saddam for his crimes, just as I do not think it was wrong for the State of Israel to execute Adolf Eichmann in 1962 for his part in the Holocaust.
I do, on the other hand, question why he was executed now, before his trial for genocide against the Kurds had been completed. Without diminishing the tragedy of the deaths of the men of Dujail who were murdered after an assassination attempt on Saddam (his conviction on this charge led to the death penalty), I think that it would have been much better if the full range of his crimes had been dealt with through several trials.