Mario Kart 7 is seeing Nintendo bring about some radical changes to how they approach online. In Mario Kart 7 every player now has the ability to name and create a community page, every one of these pages has a name and a community code, the latter will come in the following format: XX-XXXX-XXXX-XXXX. The bottom screen, in the image to the right, also has a 'search by' field just above your favourites, suggesting you can search by community names also.
In Mario Kart 7 when one player adds another player, whatever name that friend has at that time, becomes their display name in Mario Kart 7. This will likely be the case with other games down the line that use Nintendo's new "communities system". Communities are online groups formed around customizable play styles, in Mario Kart 7 this provides players with options to determine which karts, power-ups and tracks will appear in their community's online matches.
A single player can invite a group of up to eight players, individually one-by-one, or collectively using the "group invite" feature. The extent of this invite feature - only people online, only people playing Mario Kart, is uncertain at this point in time, but I think it's safe to say players will have the option to contacting those offline, by way of the new messaging system in place. The group invitations can be set to either private or public, with specific game settings/rules and tracking options available to the creator of the community page. Every community page will also have it's own leader-board.
You can install a Mario Kart Channel app on the 3DS to check if your friends are playing, from the channel you join games instantly when carts are insterted. The Mario Kart Channel will display the top 100 most active communities.
Mario Kart 7 players have the option to trade their Community information, via StreetPass initiated "Player Cards". Player Cards contain the number of races a player has participated in, their win and loss record, coins collected, ghost data and Mii racers, community information and more (the latter suggests competitions last seen in Mario Kart Wii).
Players will have the option to keep all this information private via privacy settings. Once data is exchanged, players can later race with the people they've encountered via Street Pass. When a 3DS is in sleep mode and connected to Wi-Fi, SpotPass will push new Communities and Ghost Data. Up to twenty new ghosts races will be sent this way each day.
Sounds awesome. See you at the start line!