I thought I'd post some info about Eberron, since that is the world that will be used for DDO. I had to dig into the setting last year when I was writing up my entry for the Eberron novel open call.
Eberron is very different from FR. Besides the almost steampunk elements, the entire 'feel' is different. Rather than high fantasy, there is an almost Victorian/Edwardian air about many things, a sort of pseudotechnology based on magic rather than machines.
A bit of history - once, the continent of Khorvaire was divided into the Five Kingdoms, which were the result of the split of the ancient kingdom of Galifar. Over a century ago, the 'Last War' broke out, leaving the kingdoms split into pieces, and one completely destroyed - as in nuked out wasteland. The Last War ended only two years before the official setting start. There is a lot of lingering hostility and a barely-holding peace.
There are some 'quirks' to the magic system because of the dragonshards. These are stones of great power that are used to fuel certain types of magic. They are rare and expensive, and especially useful for controlling the elements and elementals, and for creating magic items. I am sure they will be a special and valuable form of loot in DDO.
Dragonshards are also good for improving dragonmarks - another unique feature to Eberron. The *real* leaders of Khorvaire are the trading Houses, each of which specializes in a particular type of commerce. They have grown into monopolies because of the hereditary arcane sigils that appear on some of their family members. Think the magic tattoos of the Red Wizards, but genetic. They are not on every family member. The ones lucky enough to develop a dragonmark become leaders in the House.
There are several new races in the campaign setting, though according to the DDO site only one will be available in the game, at least at launch. Warforged could be described as intelligent golems. They are constructs which have been advanced to the point of free will and 'life'. The treaty that ended the Last War freed the Warforged, so they are no longer considered property. However, like all former slaves, they are still struggling against prejudice.
There are other possible races, and even the standards have quirks -
Humans - Dominant by numbers and the control of the overwhelming majority of the dragonmarked families.
Dwarves - Think the goblins of Harry Potter. Dwarves have a lock on mining and metalwork, like we are used to, but they also control the minting of coins, banking, and are ruthless debt collectors. House Kundarak carries the Mark of Warding, meaning they can protect what they have.
Elves - Aloof, regal, long lived... death obsessed? Well, some of them. The elves of Khorvaire are immigrants from the southern continent. Most have integrated fairly well with human society. Some have even formed their own country, Valenar, and are actively trying to compete with humans. Some, however, follow ancient traditions, involving not only a sort of ancestor-worship, but actual glorification of death and the undead. In their native land in the south, many families include 'undying' members, and the rulers frequently consult the Undying Court.
Halflings - I suppose you could say that there are city halflings and country halflings. In their own lands, they are tribal nomads, riding dinosaurs (no, really). In other lands, they not only blend, but hold their own. They have two dragonmarked families, one of which runs all the best inns and restaurants, and the other which provides healing services.
Those are the only races that will be included at the launch of the game. Here are the others, which hopefully will make their way in someday -
Changelings - Like their name suggest, they are shapeshifters, the descendants of interbreeding between dopplegangers and humans, though the 'mixing' took place in the distant past. They live on the fringes of society.
Gnomes - Eberron gnomes literally have a lust for knowledge. They are insatiable collectors, both of objects and facts. They love secrets, and gnome society is full of blackmail and intrigue. The same traits that make them great bards or librarians also make them excellent spies.
Half-Elves - In Eberron, they are a hybrid race rather than half-breeds - though that sort does sometimes occur. However, they do not have a homeland, and mix freely with other races. With two Houses of their own, they can compete economically quite well.
Half-Orcs - *Extremely* rare. There is very little interaction between humans and orcs, except in one small area called the Shadow Marches. There, the orcs have become reasonably civilized on a rustic level, and live much the same as the humans of the area.
Kalashtar- Kalashtar are/were a compound race like the Trills or Goa'uld, but the 'second race' is a psychic projection of a being from another plane. Kalashtar have managed to form a true hybrid of entities, so they did not supplant the host's mind. They left their realm to flee religious persecution, and in the present time new Kalashtar are born rather than created. The blending of human and spirit-being has created a new race. However, their persecutors learned where they went, and have been entering Eberron as well, but the 'bad ones' do not trouble about things like blending with the host.
Shifters - Like changelings, shifters are the result of strange human breeding (humans, sluts of the multiverse), this time with lycanthropes. Their traits and temperaments depend on what sort of animal nature is in their blood. They live in the wilder areas, generally getting along well with rangers and druids. I heard one person on a board describe them as a race of Wolverines.
Most of the classes seem to function like regular D&D. Religion is a bit different, since the gods are aloof and distant. It isn't even clear where clerics and paladins get their spell abilities from, since a cleric can be considered "corrupted" by his church and still cast spells.
There is one non-standard character class called the artificer. Artificers are magical jack-of-all-trades, with most of their skills centering around magic items rather than spell casting.
Assorted oddities - It is considered normal for people to carry identification papers, at least for the middle and upper classes. Those traveling across national borders need traveling papers. One can also possess letters of credit, which show that you have funds deposited at a bank. And much like the old privateers, an adventurer could obtain a letter of marque. All war-era letters were canceled at the end of the war, but in the country of Breeland it is still considered smart to get one before going exploring.
Life in Eberron is... interesting. Airships cross the sky, and the lightning rail zooms across the land. Ships with harnessed water-elementals speed over the water. House Lyrandar, which carries the Mark of Storms, hires out raincallers to help farmers. Magebred animals populate successful ranches and farms.
Whew, that's a lot for one go. I hope it helps explain a few of the workings of Eberron, and I hope DDO is fun.