Well, we all prolly saw this coming, since SEGA already has announced this game's release to be holiday 2011.
Gamestop's website speculates the release date to be december 31s- wait what? The last day of 2011?! Kinda weird imo, since this year is Sonic's anniversary, not next year xD.
Im pretty sure this is just speculation though, and it'll definitley change later on.