A new Mario Kart 7 trailer has been released showing some new footage, as showcased by Official Nintendo Magazine UK.
In addition to this, the Japanese Mario Kart 7 website has released information on the tracks, characters and items in the game: http://www.nintendo.co.jp/3ds/amkj/. They are keeping 2 characters secret.
Information on the blue shell and Lucky 7 powerup has also been cleared up. The blue shell moves along the ground hurting everyone in the way until it reaches the player in first position and then flies into the air and explodes them. The Lucky 7 on the other hand surrounds the player with 7 different items; however the player can only use one item at a time.