No, it's not the long-awaited Sega competitor to Mario Paint. Sonic Colors
has been announced
for release on Nintendo platforms this holiday, promising a "seamless" combination of 2D and 3D gameplay. The story involves Sonic and Tails exploring a theme-park like world while rescuing small colorful beings called Wisps, which Dr. Robotnik incidentally wants to capture--sounds pretty basic and safe so far, not unlike the old Genesis games. I'm not too worried about the DS version, considering both Sonic Rush games turned out really well but I don't want Sega to over-saturate consoles with Sonic games, especially with Sonic 4 so close to reviving the long-mediocre series.
There's some concept art at the official Sega blog, and an incredibly brief teaser below.