Mario and Sonic will appear together in a game for the first time in Mario & Sonic at the Olympic Games, announced today by Nintendo and SEGA. Based on the upcoming Beijing 2008 Olympic Games, a lineup of familiar characters including Mario, Sonic, Luigi, Knuckles, Yoshi, and Tails will compete in a variety of events on the Wii and DS. Mario & Sonic at the Olympic Games is scheduled for a Holiday 2007 release.

Link: Official Site
Link: NOA Press Release
Link: NCL Press Release
Link: SOA Press Release
Link: Sega Co. Press Release