It's nothing new to see online stores such as Amazon distributing codes for downloadable games, but GameStop appears to be one of the first to offer games on the eShop.
As you'd expect, pricing and purchase restrictions are exactly the same as on the eShop itself. What will make this worth it for some consumers is the ability to use gift cards and in-store credit from trading games towards the purchase of digital titles.
The library isn't terribly extensive at the moment, touting only Pushmo and Virtual Console title Super Mario Land 2: 6 Golden Coins, but it will no doubt expand at some point.
If you`re a resident of America, you can find the listing here, which will presumably be updated as GameStop adds support for more titles.