Druid (Wildheart Raiment):

Belt – Random Scholomance -
Boots – Mother Smolderweb, Lower Blackrock Spire -
Bracers – Random Stratholme -
Cowl – Darkmaster Gandling, Scholomance -  
Vest – General Drakkisath, Upper Blackrock Spire -
Spaulders – Gizrul the Slavener, Lower Blackrock Spire -
Kilt – Baron Rivendare, Undead Stratholme -
Gloves – Random Blackrock Spire -

Hunter (Beaststalker Armor):

Belt – Random Lower Blackrock Spire –  
Boots – Nerub’enkan, Undead Stratholme –  
Bindings – Random Stratholme –  
Cap – Darkmaster Gandling, Scholomance –  
Tunic – General Drakkisath, Upper Blackrock Spire –  
Mantle – Overlord Wyrmthalak, Lower Blackrock Spire –
Pants – Baron Rivendare, Undead Stratholme –
Gloves – War Master Voone, Lower Blackrock Spire –

Mage (Magister’s Regalia):

Belt – Random Stratholme, Lower Blackrock Spire -  
Boots – Postmaster Malown, Stratholme -  
Bindings – Random Lower Blackrock Spire -  
Crown – Darkmaster Gandling, Scholomance -  
Robes – General Drakkisath, Upper Blackrock Spire -
Mantle – Ras Frostwhisper, Scholomance -
Leggings – Baron Rivendare, Undead Stratholme -
Gloves – Random Scholomance -

Paladin (Lightforge Armor):

Belt – Random Stratholme -
Boots – Balnazzar, Stratholme -
Bracers – Random Scholomance -
Helm – Darkmaster Gandling, Scholomance -
Breastplate – General Drakkisath, Upper Blackrock Spire -  
Spaulders – The Beast, Upper Blackrock Spire -
Legplates – Baron Rivendare, Undead Stratholme -
Gauntlets – Emperor Dagran Thaurissan, Blackrock Depths -

Priest (Vestments of the Devout):

Belt – Random Blackrock Spire
Sandals – Maleki the Pallid, Stratholme -
Bracers – Random Scarlet Stratholme -
Crown – Darkmaster Gandling, Scholomance -
Robe – General Drakkisath, Upper Blackrock Spire -
Mantle – Solakar Flamewreath, Upper Blackrock Spire -
Skirt – Baron Rivendare, Undead Stratholme -
Gloves – Archivist Galford, Scarlet Stratholme -

Rogue (Shadowcraft Armor):

Belt – Random Lower Blackrock Spire -
Boots – Rattlegore, Scholomance -
Bracers – Random Stratholme -
Cap – Darkmaster Gandling, Scholomance -
Tunic – General Drakkisath, Upper Blackrock Spire -
Spaulders – Cannon Master Willey, Scarlet Stratholme -
Pants – Baron Rivendare, Undead Stratholme -
Gloves – Shadow Hunter Vosh’gajin, Lower Blackrock Spire -  

Warlock (Dreadmist Raiment):

Belt – Random Stratholme -
Sandals – Baroness Anastari, Undead Stratholme -
Bracers – Random Blackrock Spire –

Mask – Darkmaster Gandling, Scholomance –

Robe – General Drakkisath, Upper Blackrock Spire -  
Mantle – Jandice Barov, Scholomance -
Leggings – Baron Rivendare, Undead Stratholme -
Wraps – Random Scholomance -

Warrior (Battlegear of Valor):

Belt – Highlord Omokk, Lower Blackrock Spire -
Boots – Kirtonos the Herald, Scholomance -
Bracers – Random Blackrock Spire -
Helm – Darkmaster Gandling, Scholomance -  
Breastplate – General Drakkisath, Upper Blackrock Spire –
Spaulders – Warchief Rend Blackhand, Upper Blackrock Spire -
Legplates – Baron Rivendare, Undead Stratholme -
Gauntlets – Ramstein the Gorger, Undead Stratholme -

Oh, and apparently you can start the actual questy part of each quest chain, and it won't require you to actually have the set pieces until the final step.

Which is cool.

Here is a great link for upgrading the Tier 0 set through quests:

http://www.wowwiki.com/Tier_0.5

• Druid: Feralheart Raiment
• Hunter: Beastmaster Armor
• Mage: Sorcerer's Regalia
• Paladin: Soulforge Armor
• Priest: Vestments of the Virtuous
• Rogue: Darkmantle Armor
• Shaman: The Five Thunders
• Warlock: Deathmist Raiment
• Warrior: Battlegear of Heroism

I started mine even tho I am still missing 4 pieces of the Wildheart set.