Held: The Eighth Amendment bars Louisiana from imposing the death penalty for the rape of a child where the crime did not result, and was not intended to result, in the victim’s death.

By adding the qualifying phrases, what is the Court trying to say?  The significance of "Where the crime did not result, and was not intended to result, in the victim's death," is hard to understand.  If an act results in, and was intended to result in, a victim's death, then it's got a special name:  Murder. 

So why, when it's an up or down question, add in this qualifying phrase?  Can it be chalked up to sloppy writing, or is it intended to distinguish a new classification of crime, the rape/murder of a child, that will be treated differently than your garden variety murder?  Perhaps when the Supreme hold the death penalty unconstitutional for the murder of an adult, this will allow them to distinguish the rape/murder of a child?

It could happen. 

See also Orin's quick analysis at Volokh, which seems to think well of this quote from Justice Alito's dissent:

These policy arguments, whatever their merits, are simply not pertinent to the question whether the death penalty is “cruel and unusual” punishment. The Eighth Amendment protects the right of an accused. It does not authorize this Court to strike down federal or state criminal laws on the ground that they are not in the best interests of crime victims or the broader society.

Orin also raises the question of how to square the Court's holding, that the death penalty is unconstitutional for crimes not resulting in death, with the death penalty for treason.

My initial reaction is that these nitpick individual points raised by the majority.  While they may be sound arguments, they fail to address the totality of the majority holding.