Sonic Colours is a new Sonic the Hedgehog game - yes, it's "a brand new high speed action adventure in which Sonic the Hedgehog races through incredible theme park inspired worlds to rescue a colourful alien race from the clutches of Dr Robotnik... sorry! Dr Eggman". Sonic Colours will be available on the home video game system Wii and the Nintendo DS system late in 2010.
Really, that's most of what you need to know. However, if you really crave more info,
it's all here.