It’s nothing confirmed, but the Sonic Stadium forums have stumbled upon images for the anticipated multi-generational Sonic Generations as well as Mario & Sonic at the London 2012 Olympic Games. You can see the pic of the latter after the break.
I know it probably wouldn’t be the final box art, but I kind of like that image of the two Sonics with just a white background. It would be pleasantly simplistic and non-pretentious, and possibly get me more excited for the game (if that’s at all a legitimate reason). Sonic Generations will be coming out this year for PlayStation 3 and Xbox 360, while little information at all (technically, it hasn’t even been announced yet) is known about the next Olympic mash up of the Mushroom Kingdom and… the Zones.