Samera has posted information on Dragonmarks which will make be available in Module 4.1:
Three thousand years ago the first dragonmarks appeared in the elven kingdom of Aerenal. Strange patterns on the skin, more an elaborate birthmark than a tattoo, they gave their bearers magical abilities that have been a source of power and conflict for centuries.
The first two dragonmarks, the Mark of Shadow and the Mark of Death, appeared on the elven bards known as phiarlans and the necromancers of House Vol. As the two houses grew in power, House Vol began to experiment with the blending of elven and dragon blood. This was seen as an abomination by both races, and the decision was made to destroy the Mark of Death. Every blood member of the house was brutally slaughtered, and the Mark of Death has not been seen since.
Through the centuries these marks appeared in other races and bloodlines - the Marks of Hospitality and Healing on the halflings of the Talenta Plains, the Mark of Scribing on the gnomes of Zilargo, the Marks of Making, Sentinel, Passage, and Handling on the humans of Galifar, the Mark of Warding on the dwarves of the Mror Holds, as well as the Marks of Storm and Detection on Half Elves and Mark of Finding on the humans and half-orcs of the Shadow Marches.
The twelve dragonmarked bloodlines formed thirteen great houses, where the power of their marks is the source of economic and political power across Khorvaire and into Xen'drik. A member of any such house is beholden to no king, and it is these marks that allow for such wonders as the lightning rails, airships, and even warforged.
The dragons of Argonnessen recognize dragonmarks as part of the Draconic Prophecy, and study their meaning even as they resent their appearance on the so-called "lesser races." It has been rumored that in their study they have found a way to quickly and accurately check the bloodline of a lesser race against the prophecy and that of the great houses...

Dragonmarks in Dungeons & Dragons Online

Dragonmarks are feats that come in three tiers of power, Least, Lesser, and Greater. These are restricted by race and neither Drow nor Warforged can be dragonmarked.

Least Dragonmarks grant a (passive) +2 bonus on a single associated skill and the ability to use a single spell-like ability three times per day. When this feat is purchased, a dragonmark will appear on the player's skin (the mark can be removed from your character's face by unchecking the relevant box in the Options Menu). The caster level for your dragonmark is equal to your character level, and the saving throw DC is 10 + the level of the spell + your Charisma modifier. Once a least dragonmark is chosen, a player can no longer purchase any other least dragonmarks. The player must unlock the ability to purchase a dragonmark, but once unlocked, any character of any race (except Drow or Warforged) on that account of any level can purchase a dragonmark.

Lesser Dragonmarks can only be purchased if the player already has a Least Dragonmark and is at least 6 th level. This bestows a second spell-like ability twice per day and gives you one extra use/day of your Least Dragonmark.

Greater Dragonmarks can only be purchased if the player already has a Lesser Dragonmark and is at lest 9 th level. This bestows a third spell-like ability once per day and gives you one extra use/day of your Least and Lesser Dragonmarks.