Why is this relevant? iPods and iPads have nothing to do with cell phones, except that Apple happens to use the same OS for all three.

It's relevant because it's a better comparison if you're a developer thinking about committing heavily to one platform or the other. A comparison of one cherry-picked device from one lineup versus many devices from another gives you no useful information for making that decision.

Or, more pertinently: if the headline had been "all models of iPhone plus all models of iPod Touch plus all models of iPad, combined, outsell (insert one and only one Android device)", wouldn't you have been jumping all over it for this very reason?

Cell phones are just a special case of mobile computing gadgets you carry around with you. The fact that you can only do traditional carrier calls on an iPhone and not on a Touch or iPad is just a very small detail compared to the whole experience.

It's relevant if you're selling apps

In that case, you want to target Windows and Blackberry instead of OS X and iPhone OS.

("NDP Group’s smartphone survey placed the iPhone with 21%, Android platform with 28%, and Blackberry with 36%.")

er, is that a serious comment or sarcasm?

You should also throw in iPod shuffles and the Mighty Mouse if you are going to just be making up arbitrary, non-competitive market space, thresholds.