The highlight of the announcement would seem to be the "any accepted form of payment" bit, meaning that players can trade games for credit toward PC downloads. It's worth noting that GameStop isn't the first company to offer such a deal. Amazon also allows users to apply trade-in credit toward PC downloads (or any product on Amazon, for that matter).
The first game to be offered by GameStop's "in-store digital purchase" program will be Deus Ex: Human Revolution. Those who purchase the digital version will also receive downloads of the original Deus Ex: Game of the Year Edition and Deus Ex: Invisible War. Customers will also receive the "Explosive Mission" DLC and double PowerUp Rewards points.
Interestingly, Human Revolution is cited as the first of "many" games for the program, meaning that GameStop's current downloadable catalog doesn't apply.