Nintendo has opened an official site for Mario Kart 7. Access it here.
The site has sections for how to play, course, character, cart & customize, item and network play.
The course section mentions 16 added courses. When combined with the courses that are returning from past titles, the total becomes 32. Currently, you can see videos from Kinoko Cup and Koura Cup.
For characters, the site mentions 12 returning characters, new characters like Metal Mario, and the ability to use your Miis as your character.
The game's cart customization system lets you assemble parts in three areas: frame, tire and glider. By trading coins that you gather as you race, you can acquire additional parts.
The network play section includes many of the details that were announced at today's Nintendo Direct presentation. The game's online play option supports races between 8 players throughout the world. You can select to race against friends, people you've recently raced with, and people with whom you've done Street Pass exchanges.
As part of its networking feature, the game includes support for communities, places for your friends to gather and play together. You can create your own community, set play rules, and add friends as you like.
Example communities mentioned at the site include "Nearby Community" consisting of your neighbors and "Overseas Community" consisting of overseas players. Each player can create up to eight communities.
To join a community, you can search by the community code that you receive from friends. Nintendo will also be sending out "Recommended Communities" via Spot Pass.
The site does not mention the Mario Kart Channel feature that was mentioned in the Nintendo Direct presentation. Mario Kart Channel gathers all the info you've collected from Street Pass and Spot Pass transfers.
The official site has videos for many of its sections, so Mario Kart fans should click all the links!