According to this "exclusive" for Spanish Nintendo magazine Nintendo Acción hints at Mario and Sonic teaming up again for a winter games version of Mario & Sonic at the Olympic Games. Here's a translation from game site Sega Nerds: "Who are these two and why do they come to see each other? Find out all the details on the mystery game in the next magazine. But before that, here are some clues: games, Olympics, It's cold, It's winter..."Source: Kotaku.com
Can't say we didn't see this one coming really, if it's true. I never picked up the first game though, so I very much doubt this will be any different.