Making a surprise appearance at Satoru Iwata's keynote earlier today, Reggie revealed that alongside continued DSiWare support and the 3D Classics feature, which will see classics remade with 3D effects, the Virtual Console will not just feature Nintendo systems.
Sega's Game Gear and NEC's TurboGrafx-16 will be supported, which means you can expect Sonic and Bonk titles to reappear once more. Keep in mind, however, that these are not really "new" systems when taking the Wii's Virtual Console into account as well — many of the games created for Game Gear were completely identical to Master System games, while the TurboGrafx-16 obviously isn't even a handheld at all, although there was a portable device that allowed you to play TG16 games on the go called the TurboExpress.
Aside from the addition of these two systems to the 3DS Virtual Console, no specific games have been announced, so we're not sure if we can expect new Master System/Game Gear and TurboGrafx-16 titles from this, or if Sega and Hudson will simply be moving over games already available on the Wii. We'll bring you any news as it's made available.