No idea what the game is but Sonic Team is supposed to announce a new title next month. However, a list of formats already doing the rounds includes the Vita, and after Sumo Digital's top job on Sonic All-Stars Transformed, why not?
More at Sonic Stadium, who categorize it as a level-based, multi-character game with the Vita version being the same as the big consoles and the 3DS getting a cut-down version, chortle! Players can use different characters to access new parts of each level, so far so Sonic! Hope to hear much more next month.