It's been confirmed that pauldrons, greaves and the cuirass are now merged and part of a single piece called "armour" (or 'armor' if you are that way inclined).
Yet we also have numerous screenshots of the iron armour with quite a bit of variety: cuirass with no pauldrons, huge metal pauldrons, one bone pauldron.
I think it's fair to say these will be different individual items in the game (as we know smithing cannot alter an items appearance), probably all simply called "Iron Armour".
My theory (which may be a bit wacky) is that armour is now 'modular' in the Creation Kit, the best example I can think for this is the creatures in Fallout, a case in point being the Super Mutants, in the Geck under their model tab you can pick and choose which bits to display, different helmets, armour etc. So for example Uncle Leo in Fallout 3 is only wearing a pair of pants and boots, while Super Mutant Masters are fully armoured - in the Geck they have certain bits enabled or disabled under the model tab.
My theory is that armour in Skyrim now works in the same way, in the Creation Kit we might be able to, say, select Iron armour and then under a similar "models" tab we could pick and choose which bits to display.
How this ties into modding is that it may make seperate pauldrons/greaves/cuirass possible in the Creation Kit with relative ease, by simply choosing to display a pauldron and deselecting the cuirass part, providing of course that Skyrim has unused "body slots" like Tail in Oblivion or the more numerous BAO1/BAO2/Nosering etc in Fallout.
Again this is just speculation on my part and we will know for sure when the game comes out, but it's the only theory I can come up with which explains all the variety in Iron armour (without have hundreds of different nif files, I think modular armour would save on disk space).
Does anyone think this is a possibilty? Or am I just mental?