GameZone has published an interview with Turbine's Ken Troop and Dave Eckelberry, in which the lead designer and senior game systems designer answer a batch of questions about Dungeons & Dragons Online. Here's a bit to start you off:
Q: Will mages have to carry reagents for spellcasting? Will armor and weapons deteriorate with use?
A: Yes, spellcasters carry components. Those same spells in pen-and-paper D&D that require a material component require a component in D&D Online. For most spells, these components will be relatively easy to find, keep track of, and replenish. The character can restock only a few inventory slots without having to pay a great deal of attention to the process. A few spells, iconic to D&D, have harder-to-find, or at least more expensive, components.
Armor and weapons can suffer damage in combat; characters who suffer damage may also suffer some item deterioration depending on the quality and durability of their equipment, and the strength of the blow involved.
A primary goal of this system is to preserve the economic balance in the world of Dungeons & Dragons Online. Spellcasting characters mostly suffer from needing to reload through components, melee-focused characters must deal with item wear, and ranged-combat characters must replenish their ammunition.