The highest perk in the Smithing tree is the ability to create Dragon Armor and improve it twice as much. Does anyone know if this type of armor is considered heavy or light? Or do both heavy dragon armor and light dragon armor exist?

There are indeed versions of both.

I would assume both light and heavy, but I am not sure.

Both...makes no sense otherwise.

both light and heavy

Since when has there been both light and heavy versions of the best base armour in the game in an Elder Scrolls title? I'd wager that Dragon Armour is heavy, and there will be a Light equivalent.

The light and heavy armor perk branches merge together at dragon armor, so there'll probably be light and heavy versions. I hope there are shortswords that you can dual wield. If you can do it with maces, then why not swords?

Maybe Dragonbone for heavy and Dragonscale or Dragonhide for light?

The "Light Equivalent" is a different type of armor, also made from dragons. It falls under the same category.

Appealing to precedent really doesn't get you anywhere. Skyrim's main story is all about dragons, and if they're going to have dragon-based equipment, then it's only sensible that they'd let everyone have a taste. And I would argue that Morrowind didn't have any equivalencies at all, Ebony and Glass were roughly equivalent, but Daedric was in a class of it's own.

Of course, that was back when Bethesda wasn't terrified of putting items into the game that were actually rare. /depressed.

Oh well. Maybe Skyrim will some good loot.

I think you misunderstood me. In Morrowind there was Glass/Daedric/Adamantium. Each of these were very different for very different armour classes. In Oblivion, there was Amber/Madness. Amber is the light armour equivalent of Madness, yes, but it's not like making two sets of armor - Dragon Armor (Heavy) and Dragon Armor (Light) - and calling them separate armours.

Really hope there is both, always been a light armour guy and dragon armour sounds like it would be heavy

I asked this same question in a different post and was told that the light version of dragon armor is called Dragon Scale; while, the heavy version is called Dragon Bone. You can smith both of these once you get to the Dragon Armor perk.