Judging from scans taken from the upcoming issue of Spanish Nintendo magazine, Nintendo Acción, it looks like the pair will be heading to the slopes for Mario & Sonic At The Winter Games in 2010.
Translated by Sega Nerds, the cover of the Spanish magazine, shown below, apparently has the following text alongside it:
"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..."
Sounds like it's a definite.Sega has yet to officialyl confirm the title.