August 12. Those who own a 3DS and connect to the Nintendo eShop before 11:59PM EST on August 11 will be automatically enrolled into the "Nintendo 3DS Ambassador" program.
3DS ambassadorial duties mostly involve playing a bunch of free games. The status grants you access to 10 free NES Virtual Console games on September 1 before their general release (these include The Legend of Zelda, Balloon Fight and Ice Climber), along with 10 more Game Boy Advance Virtual Console games by the end of 2011. The GBA games -- like Yoshi's Island, Super Mario Advance 3, Mario Kart: Super Circuit, Metroid Fusion, WarioWare, Inc.: Mega Microgames and Mario vs. Donkey Kong -- will not be available to anyone else. Is all that enough to ameliorate early buyer's remorse?
Nintendo claims that it has sold more than 830,000 3DS systems in the US since it debuted in late March, and that it will keep momentum up with several big holiday releases. In the category of games available to everyone: Kid Icarus: Uprising in the holidays, Super Mario Land 3D in November, followed in December by Mario Kart 7.