The browser version of the store, which is also available in the game itself, is only partially functional at the moment. While it does list the categories, items, and icons for its wares, it's lacking any prices, descriptions, or ability to purchase.
It's worth a look if you want a first-hand view of the goods that ArenaNet hopes will power Guild Wars 2's profitability, of course. The categories include style, consumable, support, account, boosts, and minis.
[Update: The gemstore has since been taken down.]