I have put together a list of all tanking items that have arrived with the Secrets of Ulduar patch that a DEATH KNIGHT TANK could possibly want to use. Feel free to take a look and speak up about any items not on the list:

Crafted Items:

Item Name<<< Item Level<<< Profession<<< Source of Recipe

Waist:
Indestructible Plate Girdle<<< 226<<<Blacksmithing<<< Ulduar Drop



Emblem of Conquest Purchaces:
Item Name<<< Item Level<<< Emblem amount

Neck:
Shard of the Crystal Forest<<< 226<<< 19x

Waist:
Shieldwarder Girdle<<< 226<<< 28x



Ulduar Boss Drops:
(Including Darkruned Plate Tier Gear)
Item Name<<< Item Level<<< Source<<< Difficulty

Head:
Ironbark Faceguard<<< 219<<< Freya<<< Normal
Helm of the Faceless<<< 226<<< General Vezax<<< Heroic
Valorous Darkruned Faceguard<<< 219<<< Thorim<<< Normal
Conqueror's Darkruned Faceguard<<< 226<<< Thorim<<< Heroic


Neck:
Bronze Pendant of the Vanir<<< 239<<< Freya<<< Heroic (Hard Mode)
Fervor of the Protectorate<<< 219<<< General Vezax<<< Normal
Mark of the Unyielding<<< 219<<< Kologarn<<< Normal


Shoulders:
Shoulderplates of the Deconstructor<<< 226<<< XT-002 Deconstructor<<< Heroic
Valorous Darkruned Pauldrons<<< 219<<< Yogg-Saron<<< Normal
Conqueror's Darkruned Pauldrons<<< 226<<< Yogg-Saron<<< Heroic


Back:
Saronite Animus Cloak<<< 219<<< General Vezax<<< Normal
Cloak of the Makers<<< 226<<< Auriaya<<< Heroic
Titanskin Cloak<<< 239<<< Freya<<< Heroic (Hard Mode)


Chest:
Valorous Darkruned Chestguard<<< 219<<< Hodir<<< Normal
Conqueror's Darkruned Chestguard<<< 226<<< Hodir<<< Heroic


Wrists:
Flamewatch Armguards<<< 219<<< Flame Leviathan<<< Normal
Mimiron's Inferno Couplings<<< 226<<< Flame Leviathan<<< Heroic

Hands:
Handguards of Revitalization<<< 239<<< Freya<<< Heroic (Hard Mode)
Gauntlets of the Iron Furnace<<< 219<<< Ignis the Furnace Master<<< Normal
Valorous Darkruned Handguards<<< 219<<< Mimiron<<< Normal
Conqueror's Darkruned Handguards<<< 226<<< Mimiron<<< Heroic

Waist:
Stormtempered Girdle<<< 219<<< Razorscale<<< Normal


Legs:
Gilded Steel Legplates<<< 226<<< Flame Leviathan<<< Normal (Hard Mode)
Archaedas' Lost Legplates<<< 219<<< Auriaya<<< Normal
Saronite Plated Legguards<<< 226<<< Kologarn<<< Heroic
Valorous Darkruned Legguards<<< 219<<< Freya<<< Normal
Conqueror's Darkruned Legguards<<< 226<<< Freya<<< Heroic


Feet:
Charred Saronite Greaves<<< 226<<< Ignis the Furnace Master<<< Heroic


Rings:
Platinum Band of the Aesir<<< 226<<< Auriya<<< Heroic
The Leviathan's Coil<<< 226<<< Flame Leviathan<<< Heroic
Signet of Winter<<< 219<<< Hodir<<< Normal


Trinkets:
The General's Heart<<< 226<<< General Vezax<<< Heroic
Furnace Stone<<< 219<<< Ignis the Furnace Master<<< Normal
Heart of Iron<<< 226<<< Ignis the Furnace Master<<< Heroic
Royal Seal of King Llane<<< 219<<< Yogg-Saron<<< Normal


One-Hand Weapons:
Shiver<<< 226<<< Hodir<<< Normal (Hard Mode)
Legacy of Thunder<<< 219<<< Thorim<<< Normal
Sorthalis, Hammer of the Watchers<<< 239<<< XT-002 Deconstructor<<< Heroic (Hard Mode)
Titanguard<<< 232<<< Flame Leviathan<<< Heroic
Stoneguard<<< 219<<< Kologarn<<< Normal


Two-Hand Weapons:
(I have simply taken all two-hand Ulduar DPS drops in this category, as many Death Knights will wish to use Rune of the Stoneskin Gargoyle. Please correct me if I am mistaken.)
Lotrafen, Spear of the Damned<<< 232<<< General Vezax<<< Heroic (Hard Mode)
Hoperender<<< 219<<< Thorim<<< Normal
Stormedge<<< 219<<< Hodir<<< Normal
Worldcarver<<< 232<<< Ignis the Furnace Master<<< Heroic
Ironsoul<<< 219<<< Flame Leviathan<<< Normal
Earthshaper<<< 232<<< Yogg-Saron<<< Heroic
Rune Edge<<< 232<<< Assembly of Iron<<< Heroic
Voldrethar, Dark Blade of Oblivion<<< 239<<< General Vezax<<< Heroic (Hard Mode)
Abaddon<<< 219<<< Yogg-Saron<<< Normal