Matt Matthews @ Gamasutra: "Developers and publishers eye the used videogame segment of GameStop's business with suspicion. They believe they lose revenue when a consumer opts for a used game over a new copy -- but the first-sale doctrine effectively blocks them from claiming any part of the resale revenue.
GameStop has steadfastly maintained that used game trade-in credits more often go toward new software and actually bolster new game sales.
The retailer doesn't disclose either units or dollars of used software sales. Instead, it lumps that revenue together under a more general used product heading, along with used hardware and used accessories."