From World of Warcraft's site,
"Shattrath City, meaning "dwelling of light," was once the draenei capital. When the Burning Legion turned the orcs against the draenei, the fiercest battle was fought there. The draenei fought valiantly, but in the end, the city fell. Shattrath City was left in ruins and darkness until the Sha'tar arrived. The Sha'tar or "born of light," are the naaru who came to Outland to fight the demons of the Burning Legion. With the help of the Aldor, the city has been largely rebuilt and the Sha'tar have assumed leadership. They have managed to unify the diametrically opposed factions of the Aldor and the Scryers in a common goal: defeating the Burning Legion"
The Sha'tar is the next faction you will be meeting upon arriving on Shattrath, after having met with the Lower City representatives.
The Sha'tar's reputation grind is considerably harder; The bulk of your reputation points with the Sha'tar will be obtained through extensive questlines for your chosen Shattrath faction (which we will also cover). Once you hit 70, you're also given the choice of running Tempest Keep to keep your reputation flowing each kill.
This will be the only way of attaining Exalted.
Neutral to Honored
First and foremost, you will need to keep in mind that Sha'tar reputation until Honored is shared with your turn-ins for the Aldor or Scryers - each signet or mark turn-in will net you half the amount of aldor/scryer reputation you gain until it gets up to Honored. This is a good way to bump up your Sha'tar reputation along with your quests since there isn't really a monster you can grind on for Sha'tar reputation outside of instances.
Honored to Exalted
It is recommended you choose an allegiance by performing the initial quest for Aldor or Scryer to gain 1750 reputation before hitting Honored. Once you do, and have exhausted all your Sha'tar quests along the Outlands, it will be time to run Tempest Keep's 3 5-man level 70 instances - Botanica, Mechanar and Arcatraz.
As we will be analyzing below, your best bet for quick reputation within these instances is The Mechanar, it's a small 35-45 minute instance with a good group, and has enough monsters and bosses to boost your reputation up quickly should you run it successively and do full clears.
As an additional aid to you the player we have a chart for you to gauge how you will be getting your reputation within the dungeons, so you can plan accordingly as to when you will finally obtain Exalted if you're going for it!
Quests - ~10000 reputation
Mechanar - Normal (Neutral ~ Honored) = ~1600 reputation per run
Mechanar - Heroic (Revered ~ Exalted) = ~3000 reputation per run
Botanica - Normal (Neutral ~ Honored) = ~2000 reputation per run
Botanica - Heroic (Revered ~ Exalted) = ~3000 reputation per run
Arcatraz - Normal (Neutral ~ Exalted) = ~1800 reputation per run
Arcatraz - Heroic (Revered - Exalted) = ~3000 reputation per run