A post I put together on my ls' site as a way to keep all, or rather most, information in one place. Some of what nervosa posted is in there & it's put together from many sources. Enjoy.

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A New Land to Explore:
The new expansion takes us to the continent of Ulbuka in the far west and more specifically the island nation of the Sacred City of Adoulin Alliance. As the setting currently goes, we will be exploring the main continent which is a vast wilderness unexplored for hundreds of years and something something we get to explore it's treasures. Adoulin draws heavy influence from the Middle Ages Spain.
All those islands to the east have a purpose. With the new expansion, each adventurer (each character on any given account) will get their own island to farm, fish, raise livestock, and supposedly mine & harvest.
Also coming with the new expansion is a new set of guilds. The six new guilds will be the Information Guild, Exploration Guild, Security Guild, Amusement Guild, Transportation Guild and Workshop Guild.
New Zones:
One basic template for the Sacred City of Adoulin Alliance and jungle/forest have been shown. Nothing is really known about the areas at this time.



Within some of the new areas will be "Instanced Dungeons." To better in perspective, here is the description by Elmer over at lolZam;
Quote
A key design philosophy behind Adoulin is meeting the varied playstyles of all adventurers in Vana'diel. To that end, the developers have created a new instanced dungeon system, which can be customized for your party. The dungeon is created by assembling parts of a statue--head, body and feet. Each section controls a different aspect of the dungeon, such as dugeon size, drops and monster difficulty. Rewards are also tied to how the dungeon is set up; for example, making the monsters more difficult will also increase the chances of getting better items. However, developers assure us that everyone should come out with something if they participate. Another feature is there will be achievements along the way that will grant bonuses while in the dungeon, like performing certain skillchains or getting to chain 5. Again, this aspect of the expansion was not covered in the interview, so much will surely change before it is finalized for the expansion.
New Jobs:

The two new jobs unveiled were "Geomancer" & "Rune Fencer." Each will have their own unique play style.
Geomancer:

The Geomancer is a support Job that can buff party members and enfeeble enemies using some interesting new mechanics.
On a basic level, Geomancer functions similar to Bard. Like Bards with their instruments, Geomancers will equip bells and have a Geomancy skill and a bell skill. The combined level of these two skills will determine how effective their abilities are. Again, like a Bard without an instrument, a Geomancer can wield their power without the use of a bell, but it will reduce the effectiveness.
For party members, Geomancers can grant effects like regen, refresh and regain, or boost different parameters like STR, DEX, AGI, and so on. Against enemies, they can inflict slow, and paralysis, or other debuffs, like magic defense down or evasion down. The developers also indicated they were looking into other unique buffs and debuffs to further set the job apart, but such additions were still being proposed and tested.
Two features were also introduced for Geomancer: Polarity and Luopan. Polarity is a trait that lets the player boost their own abilities based on where they stand relative to the enemy. North for magic attack bonus, South for magic accuracy bonus, East for recast timer reduction, and West for a bonus to magic critical rate.
Luopan, which in the art of feng shui are compass boards used to detect the direction and flow of spiritual energy, are something the player can place to create an area of effect in a location of their choice. Theoretically, the Geomancer can center a Refresh Luopan AoE where the backline mages stand, or place a Regain Luopan on top of the heavy hitters. Luopan with enfeebling effects can also be placed strategically around the enemy.
However, the Luopan will have HP and can be destroyed by enemy attacks, so its positioning will be critical to its effectiveness.
Rune Fencer:

This job is meant to be the third main tank in the game after Paladin and Ninja. The Rune Fencer utilizes a variety of runes to execute magic and special abilities. While the Paladin is primarily a physical tank, the Rune Fencer is designed to tank using magical-based defenses. Elemental Runes can be used to increase elemental resistance and add elemental damage to regular attacks, similar to En-spells. Enchantment Runes are divided into attack-based and defense-based runes. Attack-based runes add big elemental damage and increase your offensive capability, while defense-based runes help your defensive capability.
Rune Fencer will be a tactical job with a variety of tools to meet various tanking situations. Elemental Runes are there to counter the different types of magic and elemental damage monsters will throw at you while allowing the player to strike back with the appropriate element in return. Enchantment Runes then let the player balance between big damage to control hate or strong defense to stay alive. In addition, Rune Fencer will be able to make other tradeoffs in battle, such as sacrificing spell duration to increase potency.
New Mobs & NPCs:

There was also a T-Rex pic shown at Vanafest, but it appears that they haven't released it to the public.