The 4E books for Eberron are still a ways away, so it might be useful to brainstorm on how to represent some setting elements in 4E for those currently running campaigns.
Right off the bat, I see Dragonmarks as a form of multiclassing with racial requirements. You take the Least Dragonmark feat, and it grants a trained skill, useful 1/encounter or 1/day ability, and the ability to take further feats. Other Dragonmark feats follow as per multi-classing examples, except that you're trading class powers for unique dragonmark-only powers. Dragonmark Heir is a paragon path, available only to those with dragonmarks. The Siberys mark is an Epic Destiny. Of course, this is for PCs. NPCs built as monsters can get the same abilties at whatever level you want them to have them.
Granted, this means all the basic dragonmark abilties will be fleeting, combat-useful stuff. The real power of the Houses will come from dragonshard focus items that can only be created and used by those with dragonmarks. Potentially you could have dragonmark-only rituals usable only by those with the appropriate dragonmark feat.
Right off the bat, I see Dragonmarks as a form of multiclassing with racial requirements. You take the Least Dragonmark feat, and it grants a trained skill, useful 1/encounter or 1/day ability, and the ability to take further feats. Other Dragonmark feats follow as per multi-classing examples, except that you're trading class powers for unique dragonmark-only powers. Dragonmark Heir is a paragon path, available only to those with dragonmarks. The Siberys mark is an Epic Destiny. Of course, this is for PCs. NPCs built as monsters can get the same abilties at whatever level you want them to have them.
Granted, this means all the basic dragonmark abilties will be fleeting, combat-useful stuff. The real power of the Houses will come from dragonshard focus items that can only be created and used by those with dragonmarks. Potentially you could have dragonmark-only rituals usable only by those with the appropriate dragonmark feat.