Announced today by Sega, Sonic is making his return as Sonic the Hedgehog 4. This game will be an episodic adventure and will be available in the summer for Wii, Xbox live arcade and Playstation network. In an interview conducted by Gamespot explained how this will be a direct sequel after the events of Sonic and Knuckles for the Genesis and can expect all of his classic moves, along with additions like leader boards. For now they have released this teaser trailer.
Source: Gamespot