Okay, let's see if I can get all I remember of this down. If I miss anything or am mistaken in something, please tell me!
Major spoilers ahead:
The closest story parallel I can draw is Scadrial from Brandon Sanderson's Mistborn series (which is awesome by the way).
So obviously, Wraeclast is a relatively small island/continent. The mainland, where the exiles are sent from, is completely controlled by a large totalitarian empire called Oriath, ruled by the Emperor. They are against the death penalty, so every time someone breaks the law, they are exiled (which generally kills the man anyways).
Wraeclast is an extremely hostile and dangerous environment, but it used to be something more. It was home to (or part of) an ancient empire, known only as the Vaal (they are even older than the so-called Eternal Empire). They apparently possessed the pinnacle of technology. The Emperor Chitus, seeking immortality (my speculation), colonized Wraeclast and built Sarn as a front for his experiments and his search for Vaal technology hundreds of years ago. He commissioned Malachai to do experiments and such for him.
Malachai was a brilliant scientist, and he discovered the use of the Virtue Gems left behind by the Vaal (and possibly also created Skill Gems Virtue Gems are Skill Gems). He was capable of implanting gems in people, granting them immortality (Lady Dialla). His experiments grew in size and grandeur, killing more and more of the people of Sarn, and turning countless more into the Undying (who finished off the rest). (Maligaro later revived these experiments using the Spike and the Baleful Gem - this created Fidelitas.)
Here's where my knowledge gets a bit hazy. Either something happened and the Emperor never succeeded in gaining immortality (which is why the new one sent the Ebony Legion to continue the experiments), or he is immortal already, and the Legion is(was?) in search of something else, now hundreds of years later.
The man named Dominus (the guy from the Beta Release Trailer) is the guy directing Piety, but I'm not sure if he's actually the new Emperor or not. He is what waits for you in the Sceptre of God.
Then you arrive.

This patch will be deployed in the early afternoon tomorrow, NZ time. That's about 14 hours away from when I post this.

Version 0.10.3
Content:
Added a new Dexterity/Strength skill - Cyclone: Initiates a spinning series of attacks as you travel to a target location.
Added two new cosmetic microtransaction effects: Sawblade Cyclone and Blue Cyclone.
Added four new Unique items, three of which were designed by our Diamond supporters. One of the Diamond Uniques is an end-game Map.
Added doors to the Vaal/Pyramid tileset.
Continued to incrementally improve the art, effects and environments and audio.


Features:
The line for each stat on the character panel now alternates colours so that they're easier to read.
The display of life bars for party members can now display reserved life values.
While on the ground, gems with quality are now marked "Superior".
You now don't get disconnected for linking too many items in chat too fast. You will still be muted for spamming them.
The information that is put on the clipboard when you hover over and item and press Ctrl+C now includes socket information and itemlevel.


Balance Changes:
Increased the damage of Incinerate by 12.5%.
Added Cyclone (which is level 24) to the quest rewards for the Marauder, Duelist and Templar (at the Normal difficulty "Lost in Love" quest), the Shadow (Cruel difficulty Hillock quest) and the Ranger (Cruel difficulty Brutus quest).
There are now four Energy Shield passives behind Chaos Inoculation. There are three 8% additional Energy Shield nodes and a new notable (Infused Shield), which adds a 20% multiplicative Energy Shield bonus.
Life Gain on Hit is now scaled by the Damage Effectiveness of a skill.


Bug Fixes:
Fixed a bug where it was possible for Increased Item Quantity/Rarity supports to stack too many times under some conditions.
Fixed a bug where you would not be told why you couldn't drop items with microtransaction effects on their gems.
Restored the PvP arena that uses the Ship Graveyard tileset, now that bugs with it are fixed.
Renamed the one-handed Ezomyte Axe to Butcher Axe, because the name clashed with another item.
Fixed a bug where you can't vote in a bandit fight if you portal out and back in again.
Fixed problems with the PvP announcer voice occuring at the same time as death screams.
Fixed some discrepancies between Nessa's text and her audio.
Fixed a problem with the visibility of sewer map nodes in higher difficulties.
When you get the Emperor's Road quest, the map is now updated correctly in all difficulties.
Fixed a bug where Hargan might not give you the Act Three sewer quest.
Reduced the size of the Bandit and Blackguard blood.