Excitebike 3D Classic, a remake of the NES title, will be right there for free on the North American store. Act fast, though, as you'll be paying $5.99 to download it after the first 30 days of availability have elapsed.
If you don't mind parting with some cash, you'll also be able to buy Game Boy ports Super Mario Land, Alleyway and Radar Mission on day one.
The update will also add the ability for DSi and DSi XL owners to transfer "most" of their DSiWare purchases to the system (we're looking for clarification on what titles will be left behind).
But let's get to the really important news: Nintendo's eShop will also arrive alongside PokéDex 3D, a virtual compendium of pokemon from the Black/White games. It's available as a free download (not timed) and lets you summon vast amounts of information on the critters, as well as full 3D models. It also has Street Pass functionality (unlock random pokémon by exchanging data) and QR support.
The QR feature is actually pretty neat: you can take a picture of your friend, set it as a background layer, then snap a pic of a QR code to introduce a pokémon. Now you won't have to photoshop all your poké-snaps!