The site reports that the port of the sequel is at least marginally improved over the first iPhone Sonic in terms of control responsiveness, though it still relies on a virtual D-pad and button. Despite the multiplayer capability of Sonic 2 on Genesis, however, this iPhone port is strictly a solo game. Tails follows behind Sonic as an AI-controlled character, but can't be operated by a second player.
If Sonic 2 does make it onto the App Store next week, it means enough of us bought the first game to make continued iPhone emulation worthwhile for Sega, which in turn means the porting is really cheap or the first one sold really well.
Update: Sega has confirmed the existence of the game, now slated for "late April."