Sonic the Hedgehog 4: Episode 2's official Japanese release date was revealed in a trailer, with the game releasing mid-May on PlayStation Network and Xbox Live Arcade.
This Episode is the sequel to Episode 1 which was released nearly 2 years ago and was met with relatively mixed reviews. The release of the iOS and Android versions will hopefully be within a few months of the PSN and XBLA release.
Sonic the Hedgehog 4: Episode 2 will be released in Japan on 16th May. The North American release is still to be determined, but hopefully it'll be revealed soon.