Arcatraz Key quest chain starts with this quest:
1. Assisting the Consortium [Level 68] : http://www.wowhead.com/?quest=10264, a 'go talk to' quest (1200XP/72s)
2. Consortium Crystal Collection [Level 69] : http://www.wowhead.com/?quest=10265, kill a dreadlord called Pentatharon and get a crystal from him
3. A Heap of Ethereals [Level 68] : http://www.wowhead.com/?quest=10262 , repeatable quest also for Consortium reputation.
1st chain ends here : 25800XP, 510 Consortium reputation OR around 15g at 70
4. Warp-Raider Nesaad [Level 69] : http://www.wowhead.com/?quest=10205, a go-kill-him quest.
5. Request for Assistance [Level 69] : http://www.wowhead.com/?quest=10266 , find Gahruj at 47,57
6. Rightful Repossession [Level 69] : http://www.wowhead.com/?quest=10267 , get 10 boxes from around Mana Forge: Duro
7. An Audience with the Prince [Level 69] : http://www.wowhead.com/?quest=10268 , Nexus-Prince Haramad at 44,35 or so in the Stormspire.
8. Triangulation Point One [Level 69] : http://www.wowhead.com/?quest=10269 , use the Triangulation Device at 66, 33
9. Triangulation Point Two [Level 70] : http://www.wowhead.com/?quest=10275 , same thing at 28,41
10. Full Triangle [Level 70] : http://www.wowhead.com/?quest=10276 , Find Culuthas at 53, 21, 70 Elite demon.
2nd chain ends here: 1600 Consortium reputation, 71450 XP or around 60 gold if you're 70.
11. Special Delivery to Shattrath [Level 70] : http://www.wowhead.com/?quest=10280 , pretty obvious.
12. How To Break Into the Arcatraz [Level 70] : http://www.wowhead.com/?quest=10704 , the Bottom Shard of the Arcatraz Key : Pathaleon the Calculator in The Mechanar and the Top Shard of the Arcatraz Key : Warp Splinter in The Botanica. Pretty obvious if you know where they're located, huh.
The quest chain doesn't stop here, there's also
13. Harbinger of Doom [Level 70] after : http://www.wowhead.com/?quest=10882
After this 3rd quest chain, you get around 40g and your Key to the Arcatraz : http://www.wowhead.com/?item=31084