That is, according to "leaked" press release on a Czech website. The inevitable sequels to Mario and Sonic's last Olympic outing takes the two to the London Olympics via the Wii and the 3DS.
Previous Mario and Sonic outings took them to the Beijing and Vancouver Olympics.
Apparently, new sports such as soccer and (horseback?) riding are being introduced in still unrevealed sequel, with over 50 Olympic sports to chose from. The release date is TBA, but something tells me that it'll be no later than the 2012 Summer Olympics. Call it a hunch.
Kotaku is following up with Sega for comment.
UPDATE: Sega just confirmed the game's existence over on Twitter.